SCIENTISTS say that the vaccines could be achieving this by priming the innate immune response to fight.
The way that Covid-19, the infectious respiratory disease caused by the SARS-CoV-2 virus, progresses is different for everyone.
Although some people experience no or only mild flu-like symptoms and emerge unscathed from the infection, some require hospitalization and intubation due to respiratory failure and varying levels of organ support. For other people, it is fatal.
Termed “interindividual variation,” health experts have largely attributed these differences in disease progression and outcome to differences in immune function.
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Older adults, men, those with preexisting chronic health conditions, and people from minoritizedTrusted Source communities are more likely to have severe Covid-19 and die.
When it comes to matters of immunity, however, there is another factor that comes into play: vaccination history.
Vaccines are key elements that train the immune system to fight a variety of pathogens that cause people to fall ill.
They also stimulate the “innate” immune response, which is the body’s first line of defense against invaders.
This is the part that has spurred scientists to investigate whether or not previous vaccinations can provide protection against other diseases, including Covid-19.
The notion that old vaccines might help in the fight against Covid-19 has persisted in the scientific community since the early days of the pandemic.
So far, live attenuated vaccines — such as the measles, mumps, and rubella (MMR) vaccine and the bacillus Calmette-Guérin (BCG) vaccine against tuberculosis — have dominated research and discussions on the matter.
For BCG, for example, some researchTrusted Source has suggested that the vaccine can “enhance the innate immune response to subsequent infections” and reduce respiratory tract infections.
Newer studies, however, have looked into inactivated vaccines — particularly the diphtheria, tetanus, and pertussis (DTP) vaccines — to see if previous inoculations translate into less severe manifestations of Covid-19.