Tag: covid vaccination

Prior COVID Infection Results in Robust Immunity after Vaccination

Vaccine injection
Image source: NCI on Unsplash

New research published in the journal JCI Insight shows that immune responses to the Pfizer-BioNTech mRNA vaccine differ significantly in individuals depending on whether or not they had a prior COVID infection. Notably, those who had COVID before vaccination produced a surge of antibodies after the first dose, with little or no increase seen after the second dose. The opposite pattern was observed in infection-naïve individuals.

“Our study shows that the presence of immune memory induced by prior infection alters the way in which individuals respond to SARS-CoV-2 mRNA vaccination,” explained first author Professor Steven G. Kelsen. “The lack of response after the second vaccine dose in previously infected individuals is especially relevant, because it could mean that some people may require only one dose or could potentially skip the booster shot.”

Prof Kelsen and colleagues carried out the study in health care workers, some having previously tested positive for SARS-CoV-2 infection and others never having been infected. The researchers measured levels of neutralising antibodies in blood samples taken at three different time points, including before vaccination and after each vaccine dose. They also performed qualitative assessment for local reactions and systemic symptoms, such as fever, headache, and fatigue, associated with vaccination.

While levels of neutralising antibodies hit their maximum in some people with prior COVID after the first vaccine dose, individuals with no history of infection showed massive responses after the second dose. Those high levels also plummeted quickly, while the COVID group retained longer lasting immunity, despite the lack of response to a second dose. However, prior infection was also linked to more frequent and longer-lasting adverse reactions to the vaccine.

“Previous studies had similarly reported long-lasting immunity and strong immune reactions in COVID patients,” Prof Kelsen said. “We now provide new information on how prior infection interacts with vaccination in terms of measurable immune response and how individuals react to mRNA vaccines based on infection history.”

The next steps for Prof Kelsen and collaborators are to modify their neutralising antibody assay to detect Omicron and other SARS-CoV-2 variants. “We also are interested in understanding how long protection from a booster dose of the vaccine lasts,” he said.

Source: EurekAlert!

Study Confirms COVID Vaccination does not Affect Fertility in IVF

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Vaccination against COVID did not affect fertility outcomes in patients undergoing in-vitro fertilisation (IVF), according to a new study. The findings, which were published in Obstetrics & Gynecology, add to the growing body of evidence providing reassurance that COVID vaccination does not affect fertility.

Investigators compared rates of fertilisation, pregnancy, and early miscarriage in IVF patients who had received two doses of vaccines manufactured by Pfizer or Moderna with the same outcomes in unvaccinated patients.

“The study found no significant differences in response to ovarian stimulation, egg quality, embryo development, or pregnancy outcomes between the vaccinated compared to unvaccinated patients.” said first author Devora Aharon, MD.

The study involved patients whose eggs were frozen and then thawed for in vitro fertilisation and womb transfer, and patients who underwent medical treatment to stimulate the development of eggs. The two groups of patients who underwent frozen-thawed embryo transfer (214 vaccinated and 733 unvaccinated) had similar rates of pregnancy and early pregnancy loss. The two groups of patients who underwent ovarian stimulation (222 vaccinated and 983 unvaccinated) had similar rates of eggs retrieved, fertilisation, and embryos with normal numbers of chromosomes, among several other measures.

The authors of the study anticipate that the findings will ease the anxiety of people considering pregnancy. 

Patients undergoing IVF treatment are closely tracked, enabling the researchers to capture early data on the implantation of embryos in addition to pregnancy losses that might be undercounted in other studies.

Previous studies have found that COVID vaccination helped protect pregnant persons (already at greater risk from severe illness and death from COVID) from severe illness, conferred antibodies to their infants, and did not raise the risk of preterm birth or foetal growth problems.

Source: EurekAlert!

Fourth Wave Ending as COVID Becomes Endemic

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Speaking to  the media on Friday, Dr Joe Phaahla said that vaccinations had “uncontestably” lowered the rate of hospitalisations as seen by reduced hospital admissions in the fourth wave. saying that there has been a decoupling between new infections and hospital admissions and deaths. An article awaiting peer review on the medRxiv preprint server shows evidence of this in Cape Town.

Vaccinations were still lower than expected, despite a renewed vaccination drive from 17 December, a situation he attributed to people focussing on their festivities. As of Thursday, 45.5% of all SA adults had received at least one dose, with just under 40% being fully vaccinated. However, only 31.6% of 18–34 year olds have been vaccinated. About one million doses have been administered to the newly opened 12–17 year age group.

In an interview with eNCA, Dr Phaahla said that he concurs with experts that COVID is heading towards becoming an endemic disease, emphasising that South Africa is prepared for this. A new dashboard is to be unveiled which will show the number of vaccinated and unvaccinated in hospitals.

Dr Phaahla has also said that the issue of mandatory vaccinations is currently being deliberated by the government and that an announcement will be made in due course. In the US, the Supreme Court blocked President Biden’s vaccine mandate for large companies, which is seen as a significant blow to his administration’s COVID response plan.

The NICD’s Dr Michelle Groome said that almost 99% of all COVID cases sequenced are caused by Omicron. Gauteng, has exited the fourth wave with a low rate of new cases (1.4 cases per 100 000) and slight (2.2%) increase, likely attributable to increased testing. All other provinces had observed a decrease in weekly incidence of new cases, save Northern Cape (21.9 per 100 000, 18.3% increase). A 14.3% positivity rate was seen as of 13 January, down from highs above 35% in mid-December.

Test positivity rate had fallen from 25–30% in the last week of 2022 to 14% on Thursday.

Quebec to Impose Health Tax on The Unvaccinated

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The Canadian province of Quebec will impose a health tax on residents not vaccinated against COVID. The province is experiencing a surge in cases, and its 12 028 deaths as of Tuesday are the highest in Canada.

The province’s Premier Francois Legault announced on Tuesday that it would be the first in the nation to financially penalise the unvaccinated.

Around 12.8% of Quebec residents are unvaccinated, yet make up nearly half of all hospital cases.

At a news conference, the premier said that people who have not had a first vaccine dose will have to pay a “contribution”, which will be “significant”.

“I think right now it’s a question of fairness for the 90% of the population who made some sacrifices,” Mr Legault said. “I think we owe them this kind of measure.”

The province also announced last week that proof of vaccination would be required to shop in government cannabis and liquor stores.

Death rates are similar to January 2021, before widespread vaccinations had begun in the province. Unvaccinated patients make up 45% of COVID ICU cases.

Hospitals in Montreal, the province’s largest city, are nearing 100% capacity and have already started limiting non-Covid related care. Quebec’s positivity rate stands at 20%.

Though such approaches are rare, some unvaccinated individuals in other parts of the world face penalties from their governments.

Greece is set to require those over 60 to pay a €100 (R1750) fine for each month that they remain unvaccinated. Austria is considering an even stiffer €7200 (R126 000) fine for unvaccinated individuals. Unvaccinated COVID patients in Singapore will also have to pay their own medical bills: with ICU stays, this has been estimated at a median of S$25 000 (R287 500).

Source: BBC News

Why Omicron May Hit Other Countries Harder

COVID heat map. Photo by Giacomo Carra on Unsplash

South Africa may have gotten off more lightly from Omicron due to widespread immunity from previous infection combined with vaccine coverage, researchers think, which may not bode well for other countries which have not completed their vaccination nor seen the worst COVID surges.

The South African Medical Research Council in collaboration with Discovery Health on Tuesday last week presented data from a large study showing  that South Africans infected with Omicron are, on average, less likely to be hospitalised, and recover faster, compared to the other variants.

Their study looked at more than 200 000 COVID cases in South Africa during a Delta-driven surge in September and October, and the start of the Omicron-driven surge in November, as that variant began increasing rapidly. About a quarter of the people in the study already have a chronic illness, putting them at higher risk of severe COVID.

The researchers found a hopeful trend: The risk of hospitalisation for adults dropped 30% during the early days of the Omicron surge from the levels seen there in September and October.

“The hospital admissions during omicron, standing at 58 per 1000 infections, are the lowest of the four COVID waves, and one-third of what we experienced during the delta surge,” said Discovery Health CEO Ryan Noach.

Why was this so? One explanation could be the immunity from COVID recovery present in the population. South Africa had experienced three huge COVID surges with low vaccination rates compared to the US and Europe.

When the Omicron variant appeared, only about a quarter of the population were vaccinated but the vast majority of residents had likely already been infected with previous variants of SARS-CoV-2. This was based on the excess mortality rate observed in the country through the pandemic, and so it is thought that South Africans likely had some immunity granted by infection.

“Thus, Omicron enters a South African population with considerably more immunity than any prior SARS-CoV-2 variant,” concluded Dr Roby Bhattacharyya, an infectious disease specialist, and epidemiologist William Hanage in a recent working paper. This means that most Omicron cases are likely to be reinfections, rather than first infections.
Other countries will not have as broad a ‘coverage’ of vaccination and previous infection as South Africa. Around 125 million Americans are unvaccinated, and a recent study estimated that about 20% of Americans had been infected with COVID from the start of the pandemic, up to August, 2021.

The data therefore suggest that a minimum of 20% of Americans who are completely ‘naive’, as scientists term it, when it comes to exposure to SARS-CoV-2.

Source: NPR

Real-world Data Shows Booster Shot Protective against Omicron

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While two doses of a COVID vaccine offered less protection against Omicron, a booster shot restored immunity back to high levels, according to real-world data from the UK.

Two doses of Pfizer vaccine provided just under 40% protection against symptomatic infection with the Omicron variant about 25 weeks after the second dose compared with around 60% protection against Delta, according to a technical briefing released by the UK Health Security Agency. [PDF]

“These early estimates suggest that vaccine effectiveness against symptomatic disease with the Omicron variant is significantly lower than compared to the Delta variant,” the agency noted in the report. However, “moderate to high” vaccine effectiveness was observed in the early period after a booster shot, they added.

The agency found that a Pfizer booster increased vaccine effectiveness to 76%. Among people who received the AstraZeneca series for their initial immunisation (which offered almost no protection against Omicron), vaccine effectiveness jumped to 71% after a Pfizer booster.

The reportcompared vaccine effectiveness against Omicron versus Delta, including 581 people who were infected with the new strain and more than 56 000 infected with Delta from the end of November to December 6.

Omicron’s reinfection rate was also much higher than Delta’s. Of 329 individuals infected with Omicron, 7% had a previous infection, compared with 0.4% of the approximately 85 000 people infected with Delta.

After adjustments for age and area, the risk ratio of reinfection for Omicron was 5.2 (95% CI 3.4-7.6).

The report also found a 20- to 40-fold reduction in neutralising antibody activity compared with the viruses used to develop the vaccines. However, a booster dose significantly improved neutralising antibodies, regardless of which vaccine was given in the initial immunisation.

Katelyn Jetelina, PhD, an epidemiologist at the University of Texas Health Science Center at Houston, said that the study data confirm what researchers have already discovered in lab research: vaccines offer significantly less protection against Omicron, and reinfection rates are expected to be high.

Dr Jetelina noted that it was reassuring to see that “we can curb infection still with a booster, which is really quite phenomenal.” However, she said that cases were likely to increase.

“I think all this data is showing us that we’re going to have a lot of infections with Omicron,” Jetelina told MedPage Today. While a high rate of infection does not necessarily translate to severe illness, Dr Jetelina said that she is concerned about population-level outcomes resulting from a flood of new cases.

“That’s where I get a bit more nervous,” she said. She pointed out that “even if the rate of severe disease is low […] those numbers start adding up real quickly.”

The UK Health Security Agency advised interpreting the results with caution, due to the low number of Omicron cases. Additionally, more data are needed before scientists can determine how well vaccines will work against severe illness, hospitalisation, and death from the Omicron strain.

“It will be a few weeks before effectiveness against severe disease with Omicron can be estimated,” the agency stated. “However, based on this experience, this is likely to be substantially higher than the estimates against symptomatic disease.”

Source: MedPage Today

Vaccine Trial Will Determine Moderna Efficacy in People with HIV

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A highly anticipated clinical trial in eight sub-Saharan countries is the first to specifically evaluate the efficacy of a COVID vaccine in people living with HIV, including those with poorly controlled infections. It also is the first study to evaluate the efficacy of vaccines – in this case, Moderna mRNA-1273 – against the Omicron variant of SARS-CoV-2.

In addition to examining the efficacy of COVID mRNA vaccines in people living with HIV, the study investigators seek to identify the optimal regimen for this population and how it might vary based on whether an individual has previously had COVID-19 or not.

The trial will be conducted in East and Southern Africa – regions of the world that have been highly impacted by HIV. It is expected to enrol about 14,000 volunteers at 54 clinical research sites in South Africa, Botswana, Zimbabwe, Eswatini, Malawi, Zambia, Uganda and Kenya, where adult HIV prevalence ranges from 4.5% to 27%.

“Sub-Saharan Africa has been hit hard by the COVID pandemic, but access to effective vaccines, especially mRNA technology, has been very limited,” said Dr. Nigel Garrett, co-chair of the study and head of Vaccine and HIV Pathogenesis Research at the Center for the AIDS Program of Research in South Africa (CAPRISA). “The Ubuntu trial will provide safety data to regulators and assess correlates of protection from COVID-19, and it will answer important questions on mRNA vaccine dosage regimens among people living with HIV.”

About 12 600 people living with HIV and about 1400 who are HIV-negative are expected to be enrolled in the study. About 5000 will have previously had COVID, confirmed by an antibody blood test done at initial enrollment. All participants will receive the Moderna vaccine, but dosages and schedules will vary depending on previous SARS-CoV-2 infection. Participants living with HIV will get access to optimal HIV treatment throughout the trial.

“This region faces a huge HIV burden,” said Dr Glenda Gray, Ubuntu study protocol lead adviser and president of the South African Medical Research Council (SAMRC). “Although safe and effective vaccines have been developed for COVID-, HIV and COVID are on a collision course,” she added. “The impact of COVID-19 on people living with HIV is a concern for the continent, particularly in light of the recently-sequenced omicron variant set to drive South Africa’s fourth wave and further infections globally.”

Dr Philip Kotzé, one of the lead study investigators, said the Ubuntu study would not be possible without the crucial participation of rural communities across Southern and East Africa. “These communities have been disproportionately impacted by the twin pandemics of HIV and COVID-19, and they now have an unprecedented opportunity to help advance science and improve our understanding of the immune response to SARS-CoV-2 in the context of HIV.”

Dr Larry Corey, principal investigator of both the HIV Vaccine Trials Network (HVTN) and the COVID-19 Prevention Network (CoVPN), and co-leader of the network’s vaccine testing pipeline, said this study seeks to address the knowledge gap around HIV status and COVID vaccination.

“Vaccination and treatment are critical for those who face the dual threat of HIV and COVID, as they remain at high risk of acquisition and transmission and potentially can be the origin of future variants,” Dr Corey said. “It is imperative that we as scientists and as society double-down on global efforts to find and make available effective vaccines and treatments. This study represents an important step forward in our efforts to reduce the burden of COVID among HIV-infected persons and understand whether current dosage regimens are adequate.”

Source: HIV Vaccine Trials Network

Should Unvaccinated-by-choice COVID Patients Get Less Priority?

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A new opinion piece provides an exhaustive examination of the ethics of using hospital resources on unvaccinated-by-choice COVID patients with pneumonia, versus patients with other serious but slower illnesses.

In his article published online in the Annals of the American Thoracic Society, William F. Parker, MD, PhD, looked at cases in which hospitals delayed time-sensitive and medically necessary procedures for vaccinated adults when they were overwhelmed with unvaccinated patients who had severe, life-threatening COVID pneumonia and suggested an ethical framework for triaging these patients.

“These vaccinated patients are directly harmed when hospitals use all their resources to care for the many unvaccinated patients with COVID,” he wrote.  “For example, delaying breast cancer surgery by just four weeks increases the relative risk of death from the disease by 8%.”

Dr Parker argues for a contingency care standard prioritising emergency life-support, regardless of vaccination status, in order to save the most lives.  “Simply rejecting the use of vaccination in prioritisation of medical resources without analysis ignores the very real tradeoffs at play during a pandemic.  The pain and suffering of the vaccinated from deferred medical care require a deeper defense of caring for the unvaccinated.”

Eliminating double standards
He stated: “Even though the vast majority of patients who develop life-threatening COVID pneumonia are unvaccinated, hospitals still have ethical obligations to expand capacity and focus operations on caring for them—even if it means making vaccinated patients wait for important but less urgent care like cancer and heart surgeries.”

“If tertiary care centers turn inward and stop taking transfers of COVID patients from overwhelmed community hospitals, this will result in de facto triage in favor of lower benefit care and cause systematic harm to both the vaccinated and unvaccinated in vulnerable communities,” he adds.  “Hospitals must justify their nonprofit status by accepting transfers and prioritizing life-saving care during a pandemic surge.”

He cited the example of a surge in Los Angeles, when the public health department had to issue an order forcing elite hospitals to stop doing financially lucrative elective procedures and accept patient transfers from community hospitals with ICUs overwhelmed by COVID.

Reciprocity and proportionality
The principle of reciprocity supports a possible tiebreaker role for vaccination status when two patients have equivalent survival benefit from a scarce health care resource. However, a universal exclusion of the unvaccinated from life support during a pandemic surge fails the test of proportionality for reciprocity, according to Dr Parker.

Reciprocity is rewarding one positive action with another. One example of this principle is giving vaccinated people access to sporting or entertainment events that are off limits to the unvaccinated (even if negative for COVID). Proportionality is the principle that ‘payback’ should be proportional to the magnitude of the act.  For example, living kidney donors get moved way up the waitlist- the equivalent of four years of waiting time on dialysis.  This satisfies the proportionality principle.

Dr Parker points out that while the increased relative risk of death of 8% from deferring breast cancer surgery is awful, the absolute increase in risk is only one per 100, and perhaps only one per 200 for a two-week deferral.
“After the surge is over, the hospital can catch up on deferred elective surgeries,” he wrote. “The harm from a coronary artery bypass or cancer surgery delayed two weeks is real, but tiny in comparison to certain death from denying life support for respiratory failure.”

He concluded that: “There is a defensible role for vaccination status in triage as a limited tiebreaker, not as a categorical exclusion, but only in the context of a well-defined and transparent triage algorithm.  Despite the enormous financial pressure to do otherwise, elite academic centres are obligated to prioritise life support for emergency conditions to save as many lives as possible during COVID surges.”    

Source: EurekAlert!

South Africa Faces Vaccine Glut as Uptake Slows

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South Africa has asked Johnson & Johnson and Pfizer to delay delivery of COVID vaccines as it has too much stock now, health ministry officials said, as vaccine hesitancy continues to slow the immunisation campaign.

About 35% of South Africans are fully vaccinated, still only half the government’s target of 70% by year end. In the past 15 days, an average of 106 000 doses a day have been administered. At the beginning of the year, the programme had been beset by a lack of doses for a wide range of reasons, from AstraZeneca’s ineffectiveness against the Beta variant to overseas production delays. 

Deputy director-general of the Health Department, Nicholas Crisp, told Reuters that South Africa had 16.8 million doses in stock and said that deliveries had been deferred.

A spokesman for the Health Ministry said: “We have 158 days’ stock in the country at current use. We have deferred some deliveries.”

Stavros Nicolaou, chief executive of Aspen Pharmacare, which is packaging 25 million doses a month of J&J vaccines in South Africa, said most of the vaccines bound for South Africa would now be diverted to the rest of Africa, and deliveries would likely be deferred until the first quarter of next year.

A Pfizer spokesperson said: “We remain adaptable to individual country’s vaccine requirements whilst continuing to meet our quarterly commitments as per the South Africa supply agreement.”

The government has been trying to boost the rate of daily administered doses, such as with R100 ‘Vooma vouchers’ for registering to vaccinate, but even these have failed to sufficiently stoke uptake.

“There is a fair amount of apathy and hesitancy,” said Wits University’s Professor Shabir Madhi.

On Twitter, he further suggested using the excess stock for booster shots, which would “provide all single dose JJ adult recipients a JJ or Pfizer boost, and  those > 65 or immunosuppressive conditions an additional Pfizer dose if received 2 doses > 5 months ago.” 

Source: U.S. News

Immune Cells Persist 6 Months after COVID Vaccination

Image of a syring for vaccination
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A recent study shows that T helper cells produced by people who received either of the two available messenger RNA (mRNA) vaccines for COVID persist six months after vaccination, at only slightly reduced levels from two weeks after vaccination. They are also at significantly higher levels than in unvaccinated individuals.

In the study, published in Clinical Infectious Diseases, the researchers also found that the T cells they studied recognise and help protect against the highly infectious delta variant of SARS-CoV-2.

“Previous research has suggested that humoral immune response – where the immune system circulates virus-neutralising antibodies – can drop off at six months after vaccination, whereas our study indicates that cellular immunity – where the immune system directly attacks infected cells – remains strong,” said Professor Joel Blankson, MD, PhD, study senior author. “The persistence of these vaccine-elicited T cells, along with the fact that they’re active against the delta variant, has important implications for guiding COVID vaccine development and determining the need for COVID boosters in the future.”

The researchers sampled blood from 15 study participants at three times: prior to vaccination, between seven and 14 days after their second Pfizer/BioNTech or Moderna vaccine dose, and six months after vaccination. The median age of the participants was 41 and none had evidence of prior SARS-CoV-2 infection.

CD4+ T lymphocytes are nicknamed helper T cells because they assist another type of immune system cell, the B lymphocyte (B cell), to respond to antigens on viruses such as SARS-CoV-2. Activated by the CD4+ T cells, immature B cells become either plasma cells that produce antibodies to mark infected cells for disposal from the body or memory cells that ‘remember’ the antigen’s biochemical structure for a faster response to future infections. Therefore, a CD4+ T cell response can serve as a measure of how well the immune system responds to a vaccine and yields humoral immunity.

The researchers found that the number of helper T cells recognising SARS-CoV-2 spike proteins was very low pre-vaccination, with a median of 2.7 spot-forming units (SFUs, the level of which is a measure of T cell frequency) per million peripheral blood mononuclear cells (PBMCs, identified as any blood cell with a round nucleus, including lymphocytes). Between 7 and 14 days after vaccination, the T cell frequency rose to a median of 237 SFUs per million PBMCs. At six months after vaccination, the level dropped slightly to a median of 122 SFUs per million PBMCs – a T cell frequency still significantly higher than before vaccination.

Six months after vaccination, the number of T cells recognising the delta variant spike protein was not significantly different from that of T cells attuned to the original virus strain’s protein.

“The robust expansion of T cells in response to stimulation with spike proteins is certainly indicated, supporting the need for more study to show booster shots do successfully increase the frequency of SARS-CoV-2-specific T cells circulating in the blood,” said Prof Blankson. “The added bonus is finding that this response also is likely strong for the delta variant.”

Source: John Hopkins Medicine