Study shows that a 3rd dose of Covid-19 vaccine, given 6 months after the second dose, triggers a strong immune response towards Covid-19 virus, which is around 3 to 5 times more if given only the 2nd dose.
According to Bernama, Pharmaniaga Berhad vaccine specialist Dr Ajit Pal Singh Raina said that in a recent immune-persistence study by Sinovac shows that 2 doses of Sinovac’s CoronaVac vaccine triggers good immunogenicity but the neutralising antibody levels will decline after 6 months.
Despite that, a 2-dose vaccination is able to generate a strong immune memory.
Meanwhile, Ajit Pal said that the 3rd dose of CoronaVac effectively boosts neutralising titers and provides a better immuno-protection response.
He notice that this pattern is consistent with other vaccines too, such as AstraZeneca, which shows a higher concentrations of total Immunoglobulin G (IgG) antibodies after a third dose.
“It is also worth mentioning that timing for a booster dose is critical and not to be given too early.” he added.
Having said that, immunogenicity or neutralising antibody titers is defined as the ability to provoke an immune response capable of killing or neutralising viruses causing diseases.
In the interview, Ajit Pal said that the University College London (UCL) researchers found that a decay in antibody titers occurred with the other Covid-19 vaccines too, where some recipient’s antibody levels shows a decline as early as 6 weeks.
In addition, the antibody levels further reduce by more than half in the coming 10 weeks. With this happening, it is almost certain that a booster shot will be required.
He added that the findings from the study were then published as a research letter in The Lancet, based on data from over 600 vaccines.
“However, different methods and measuring units are used to measure decay at the antibody level, hence the results are not directly comparable but indicate a similar decline in antibodies over time for all vaccines.” he said.
“After initially spurning the idea of booster dose and complete understanding of how the vaccine works against the Covid-19 virus, it is clear from recent studies that protection from severe disease and hospitalisation remain high after vaccination.
“However, the surge in cases caused by the contagious and deadly variants have caused some countries to look more closely at booster shots, and some have even started administering them.”
What do you think about this? Share your thoughts!