Some viruses, such as polio, measles and mumps, do not change a lot, hence the vaccines continue to be effective. In contrast, influenza changes every year, so people receive a new flu vaccine to protect against it.
“The vaccine is the protection,” said Prof. Meital Gal Tanamy, head of the Molecular Virology Lab at Bar-Ilan University’s Faculty of Medicine. “The period of protection is dependent on the vaccine and the virus.”
“A variant is a virus that contains mutations, and if it has evolutionary advantages, it can take over in the population,” she said, adding that this is what happened with the Delta variant. “The other question is how effective against these variants the vaccines we have will be.”
Coronavirus is an RNA virus, which means it changes. However, its mutation rate is three to four times less compared with the influenza virus, which is good news for vaccine makers, Gal Tanamy said.