3rd vaccine shot can boost immunity by up to 5 times, says expert

 

A third dose of Sinovac’s CoronaVac vaccine can provide better immunity response, a study by the company shows.

KUALA LUMPUR: A third dose of the Covid-19 vaccine, given six months after the second dose, can lead to a strong, three to five-fold boost in immune response, a health expert says.

Pharmaniaga Berhad vaccine specialist Dr Ajit Pal Singh Raina said the results of a recent immune-persistence study by Sinovac showed that two doses of Sinovac’s CoronaVac vaccine induced good immunogenicity.

Although neutralising antibody levels declined after six months, a two-dose vaccination schedule generated a strong immune memory, he said in an article published on the Bernama news portal today.

“Hence, will a booster shot be necessary? The third dose of CoronaVac effectively boosts neutralising titers and provides a better immuno-protection response. This pattern is consistent with other vaccines like AstraZeneca, showing 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 said.

Immunogenicity or neutralising antibody titers is defined as the ability to provoke an immune response capable of killing or neutralising viruses causing diseases.

Citing University College London (UCL) researchers, Ajit Pal said decay in antibody titers will also be seen with other Covid-19 vaccines where antibody levels start declining from as early as six weeks.

He said the antibody reduced further by more than half in 10 weeks, confirming the need for a booster dose.

The findings were 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.” - FMT