People who are injected with the Covid-19 vaccine and who have never been infected with the virus could be very vulnerable to the new variants, according to a new British study.
Researchers at Imperial College London, Queen Mary University London and University College London studied immune responses in healthcare workers who were injected with the BioNTech / Pfizer vaccine.
Scientists found that people who had not previously been infected with Covid-19 showed very low levels of neutralizing antibodies against the original Wuhan strain, the B.1.1.7 variant first identified in Kent and B.1.351 in South Africa.
In contrast, those who had previously had a mild or asymptomatic infection and subsequently received a single dose appeared to have greatly improved protection against B.1.1.7 and B.1.351, demonstrating high neutralizing antibodies and a strong T cell response, who remember past infection.
A dose without prior infection “seems very, very low, especially against the newer variants,” said Danny Altmann, professor of immunology at Imperial. “Our message would stay here until you receive your second dose.”
But, Altmann added, a previous infection coupled with a single injection of the vaccine caused a “stupendous reaction”. “A previous infection saves your response from the variants,” he says.
The Imperial paper was published shortly after the first detailed UK ‘vaccine failure’ study, commissioned by the Government’s Scientific Advisory Group on Emergencies (Sage), found that more than 500 elderly developed symptoms of Covid-19 severe enough to be hospitalized for at least three weeks after vaccination, of which 113 subsequently died.
Sage research, undertaken by the Isarian Coronavirus Clinical Characterization Consortium, analyzed 52,280 hospital patients as of December 8, when the vaccine rollout in the UK began.
Patients who had been vaccinated more than three weeks previously and should have received immune protection against Covid-19 represented 1% of the hospitalized sample. About a fifth of this group died from the disease.
Professor Calum Semple of the University of Liverpool, co-director of Isaric, said: “This is real data showing that vaccines work, but it is not surprising that it also shows vaccine failure – mainly in the frail elderly population. ”
He added that the absolute number of people dying in this way was “very low” compared to the total vaccinated population.
The researchers say the overall results show that vaccination significantly reduces the risk of hospitalization and death, consistent with clinical trial results, although their study design did not allow them to calculate an overall efficacy figure for them. vaccines.
The United States Centers for Disease Control released a detailed case-control study this week of 417 patients in 24 hospitals, who found that BioNTech / Pfizer and Moderna vaccines were 94 percent effective in preventing hospitalization after two doses and 64 percent after one dose. Most of the people in the Isaric study in the UK had only received their first dose of Pfizer or Oxford / AstraZeneca vaccine.
The CDC is also conducting a larger survey of what he calls “breakthrough vaccine cases” of Covid-19 in the United States. As of April 20, it had received 7,157 reports of infections in fully vaccinated people, including 498 hospitalizations and 88 deaths.
“Reported vaccine breakthrough cases will represent undercount,” the CDC said, as data is incomplete and depends on voluntary reporting. “No vaccine is 100% effective in preventing disease. There will be a small percentage of fully vaccinated people who still get sick, are hospitalized, or die from Covid-19. ”
Semple made the same remark about isaric research. “We think it’s a vaccine success story, but within society at large there is suspicion of vaccine data,” he said, adding the study was a response. to “some feeling that we are not looking hard enough for vaccine failure.” .
Dr Annemarie Docherty of the University of Edinburgh, co-author of the Isaric study, said: ‘We are talking about statistics, but if it was your grandmother who was vaccinated and later died with Covid , this is a personal tragedy.