The protection of less effective vaccines against COVID-19 can wear off faster. The Sinopharm vaccine may already show signs of this decline. Clinical studies show it is 78 percent effective, but the United Arab Emirates and Bahrain are already offering boosters to people who have received the Sinopharm vaccine to boost their declining immunity.
How will we know vaccines are losing their effectiveness?
Researchers are looking for biological markers that can show when the protection of a vaccine is no longer sufficient to contain the coronavirus. It is possible that a certain antibody level sets the threshold: if your blood level is above this threshold you are in good condition, but if it is below you are at greater risk of infection.
Some preliminary studies suggest that these markers, known as protective correlates, are present in COVID-19 vaccines. Research is being carried out to find them.
“This will teach us a lot,” said H. Clifford Lane, assistant director of clinical research and special projects at the US National Institute of Allergy and Infectious Diseases.
What about the variants?
We may need reinforcements to lock down the variants, but that is still unclear.
The emergence of variants in recent months has accelerated research into reinforcements. Some variants have mutations that cause them to spread quickly. Others carry mutations that could reduce the effectiveness of approved vaccines, but right now scientists have only a handful of clues as to how existing vaccines work against the different variants.
Last month, for example, researchers in Qatar published a study of the Pfizer BioNTech vaccine, which was administered to more than 250,000 citizens of the country between December and March.
Clinical studies showed the vaccine was 95 percent effective against the original version of the coronavirus, but a variant called Alpha, first identified in the UK, reduced its effectiveness to 89.5 percent. A variant first identified in South Africa, known as Beta, further reduced it to 75 percent; However, the vaccine was 100 percent effective against both variants in preventing serious, critical, or fatal illness.