Image via 123RF
Penn State biologist David Kennedy PhD, published a paper in PLOS BIOLOGY in 2015 titled, “Imperfect Vaccination Can Enhance the Transmission of Highly Virulent Pathogens.” In it, he explains how the transmission of viruses and more severe strains by infected vaccinees could provide an opportunity for more virulent variants to spread.
The article described an experiment with a herpes virus that causes Marek disease in chickens. Vaccines against Marek disease are described as “leaky” because, although they protect chickens from getting sick, they don’t prevent them from becoming infected and transmitting the virus to unvaccinated chickens. That allows the most virulent strains that normally would die along with an infected chicken to survive and infect and kill unvaccinated chickens.
In other words, the vaccinated and unvaccinated can still spread the disease, and the vaccinated are protected from severe disease and symptoms. But what happens if vaccines don’t protect against severe disease and symptoms of these new variants? This means that conditions can be created that cause more severe disease in the vaccinated as well.
We’ve seen this with seasonal flu, where vaccines have to constantly be updated because of changes in the virus, and we’re currently witnessing it with COVID vaccines. COVID vaccines will most likely be tweaked as new variants continue to emerge, and shots may be encouraged once or twice a year. Who knows?
Many people have already received a third dose and in some countries, like Israel and Canada, a fourth dose is being offered to the elderly and immunocompromised patients. This is something people aren’t used to, so many jabs in such a short period of time, along with mandates as well.
We now know that COVID vaccines don’t stop the transmission of COVID, and that variants like Omicron and Delta are able to escape the protection that COVID vaccines provide. This is why the US Centers for Disease Control and Prevention (CDC) advises that even after they’re fully vaccinated, people should continue to mask up and socially distance in public places in part because they could still unknowingly become infected and transmit COVID to people who have and haven’t yet received their shots