COVID-19 Vaccination: Is vaccine mix-and-match safe? Do we really need a booster shot? Know what WHO has to say

Amid more infectious Covid-19 variants reported across the globe, scientists are recommending a combination of vaccine which may offer longer immunity and protection against variants.

Soumya Swaminathan, the World Health Organization’s chief scientist says that combination of Covid-19 vaccines seems to be working well against variants. She said, “It seems to be working well, this concept of heterologous prime-boost. This opens up the opportunity for countries that have vaccinated people with one vaccine and now are waiting for the second dose they have run out of, to potentially be able to use a different platform vaccine.”

But, she said that early data from the UK, Spain and Germany suggest a “mix-and-match” regimen using two different types of vaccines generates more pain, fever and other minor side effects compared with two doses of the same inoculation, a report in Bloomberg said.

Swaminathan adds that the so-called heterologous prime-boost combinations appear to spur a more robust immune response, leading to higher levels of antibodies and the white blood cells that kill virus-infected cells.

Countries, meanwhile, have already started testing a combination of vaccines to speed up immunisation. Malaysia, for example is considering a combination of the AstraZeneca Plc and Pfizer-BioNTech shots and the government is trying to speed up immunizations to achieve population-level immunity by year-end, Science, Technology and Innovation Minister Khairy Jamaluddin said.

“We do not have the information that’s necessary to make the recommendation on whether or not a booster will be needed,” Soumya Swaminathan, the World Health Organization’s chief scientist, said in a Zoom interview Friday. The “science is still evolving.”

Such a call is “premature” while high-risk individuals in most of the world haven’t yet completed a first course of vaccination, Swaminathan said. Data from countries introducing precautionary extra inoculations later this year — particularly for vulnerable people whose immunity to SARS-CoV-2 may wane faster — will inform WHO’s guidance, she said.

Covid booster shots are likely to be rolled out in U.K. in the fall to avoid another winter surge. Seven different vaccines are being tested in volunteers in England in the world’s first booster study, Health Secretary Matt Hancock said last month.

The U.K., which has inoculated a larger proportion of people than any other major economy, has been forced to delay a planned lifting of coronavirus restrictions amid a resurgence of cases driven by the delta variant. The strain, first reported in India, is the most infectious reported to date.