LONDON: The total level of antibodies began to decrease six weeks after immunization complete with the Pfizer and Astrazeneca vaccine, and can reduce more than 50 percent more than 10 weeks, according to research published in the Lancet journal.
Researchers from the University College London (UCL) in the UK noted that if the antibody level continues to decline at this level, there is concern that the effects of protection from vaccines can also start tiring, especially against new variants.
However, they said, how fast it might happen unpredictable.
The Virus Virus Watch study also found that the antibody level was substantially higher after two doses of the Pfizer vaccine than after two AstraZeneca prevention shots, known as Covishield in India.
The antibody level is also much higher in people who are vaccinated than those who suffer from SARS-COV-2 infection before, they said.
“The antibody level follows both doses either astrazeneca or the initial Pfizer vaccine is very high, which is likely an important part of why they are so protective against severe Covid-19,” said Madhumita Shrotri from the UCL Health Informatics Institute.
“However, we found this level down substantially for two to three months,” Shrotri said in a statement.
Findings based on data from more than 600 people aged 18 years and above are consistent in all groups of people regardless of age, chronic or sex diseases, according to researchers.
The authors highlighted that even though the clinical implications of the antibody level reduced unclear, some declines are expected and the current research shows that the vaccine remains effective against severe diseases.
For Pfizer, the antibody level is reduced from the median 7506 units per milliliter (U / mL) at 21-41 days, up to 3320 U / mL at 70 days or more.
For AstraZeneca vaccines, the antibody level reduced from the median 1201 U / mL at 0-20 days to 190 U / mL at 70 days or more, more than fivefold.