New York, Jul 16 (IANS): Vaccine protection against Covid-19 is short-lived and, therefore, booster shots are important, says a new study.

"The mRNA vaccines produce the highest levels of antibody response and in our analysis confer more durable protection than other vaccines or exposures," said lead author Jeffrey Townsend from Yale University, in the study, published in the journal Proceedings of the National Academy of Sciences.

"However, it is important to remember that natural immunity and vaccination are not mutually exclusive. Many people will have partial immunity from multiple sources, so understanding the relative durability is key to deciding when to provide a boost to your immune system," Townsend added.

Since Covid-19 vaccines first became available to protect against infection and severe illness, there has been much uncertainty about how long the protection lasts and when it might be necessary for individuals to get an additional booster shot.

For the study, the team quantified the likelihood of future infection following natural infection or vaccination by the Moderna, Pfizer, Johnson & Johnson, or Oxford-AstraZeneca vaccines.

The risk of breakthrough infections, in which a person becomes infected despite being vaccinated, depends on the vaccine type.

According to the study, current mRNA vaccines (Pfizer, Moderna) offer the greatest duration of protection, nearly three times as long as natural infection and the Johnson & Johnson and Oxford-AstraZeneca vaccines.