Antibodies drop 50% within weeks of the second shot, necessitating a Covid booster.
Scientists warn protective antibodies fade quickly after two doses, so people across the UK, especially the elderly and vulnerable, may be called in for a third Covid jab.
According to studies, antibody levels created by two doses of the Oxford/AstraZeneca or Pfizer/BioNTech coronavirus vaccine may begin to decline six weeks after the second shot, and in certain cases, by up to 50% in less than three months.
While antibodies are likely to decline, this means people will be less protected from the virus.
It’s also unclear how quickly concentrations can rise in the presence of infection, a phenomenon called as memory response.
However, in preparation of losing immunity, the NHS in England will begin planning a coronavirus booster jab program in September.
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Officials have stated that a third vaccine may not be required, but scientific advisers to the government have stated that they are not taking any chances.
The Virus Watch study at UCL looked at blood samples from 552 vaccinated patients, most of whom were in their 50s and 60s.
Antibody levels varied somewhat amongst patients, however a Pfizer/BioNTech double injection produced more antibodies against the virus than two Oxford shots.
Antibody levels in the Pfizer vaccine declined from an average of 3320 units per millilitre (ml) at 70 days to an average of 21–41 days.
They dropped from 1201 units per ml at 0–20 days to 190 units per ml at 70 or more days for the Oxford jab.
The findings have been published in the Lancet as a research letter.
“Given the potentially rapid S-antibody decline suggested by these data, and given the recent advice in support of booster vaccinations from the UK’s Joint Committee on Vaccination and Immunisation, heterologous regimens, which preliminary data suggest elicit stronger antibody and T-cell responses, might provide more durable immunity and greater protection against emergi,” the authors write.
“Principally, in the light of expanding global vaccination disparities, the ethical justification for universal booster dose deployment in high-income settings should be carefully considered,” they write.
“Data on differences in peak antibody levels and rates of decrease could thereby advise targeted and equitable booster deployment,” says the study.
Eleanor Riley is an associate professor of. “The summary has come to an end.”