Received AstraZeneca, Pfizer Vaccine? Recipients May Need Booster Doses, Suggests New Study

The levels of antibody following both doses of AstraZeneca or Pfizer vaccine were initially very high, but these levels dropped substantially over the course of two-three months, said the researcher

New Delhi: For those taking Pfizer and AstraZeneca jabs, here is the latest research of your concern. New research conducted by University College London (UCL)  found that coronavirus antibody levels start declining from as early as six weeks after complete vaccination with Pfizer and AstraZeneca jabs. It can further reduce by more than half over 10 weeks, indicating the need to get booster shots, according to the researchers.

What are new findings?

The findings of the research letter published in The Lancet are based on data from over 600 people.

It has been found that antibody levels remain substantially higher after the completion of two doses of the Pfizer or AstraZeneca vaccine, manufactured in India as Covishield by Serum Institute of India (SII). According to the research, the antibodies have been found to be higher in those who have received both jabs after recovering from covid-19.

The research goes on to highlight that the clinical implications of waning antibody levels are still not clear, some decline was expected. The current research shows vaccines remain effective against severe disease and these findings remain consistent across groups of people regardless of age, chronic illnesses, or sex.

India is also in talks to include the Pfizer vaccine in the nationwide immunization programme.

According to the findings, Pfizer, antibody levels reduced from a median of 7,506 U/mL at 21–41 days to 3,320 U/mL at 70 or more days. For AstraZeneca, they came down from a median of 1,201 U/mL at 0–20 days to 190 U/mL (67–644) at 70 or more days. U/mL is units per millimeter.

 “The levels of antibody following both doses of either the AstraZeneca or Pfizer vaccine were initially very high, which is likely to be an important part of why they are so protective against severe covid-19," said Dr Maddie Shrotri of UCL Institute of Health Informatics.

However, these levels dropped substantially over the course of two-three months, according to Shrotri. He added in case it continues to drop at this rate, the protective effects of the vaccines may also begin to wear off, particularly against variants; but it cannot be yet predicted how soon that might happen.