Real-world data offers hope that mRNA vaccines are highly effective in limiting infection and presumably transmission of the coronavirus, in addition to their already known ability to prevent symptoms of Covid-19. The findings, based on research from Israel and elsewhere, are good news for containing the pandemic sooner rather than later.
A study published in The Lancet last week examined healthcare workers at Israel’s Sheba Medical Center. The study compared rates of covid-19, both with and without symptoms, among workers who received the Pfizer / BioNTech vaccine or not. As other research has shown, people were significantly less likely to get COVID-19 after receiving the first of two scheduled doses.
Within two to three weeks after the first dose, the risk of having symptomatic COVID-19 was reduced by 85%. It is important to note that the risk of covid-19 in general, including asymptomatic infection, in which a person has the virus but does not feel sick, was also reduced by 75% in that same period, according to periodic PCR tests. That’s crucial, because even people with silent infections can pass the virus to someone else. But if a vaccine greatly prevents people from getting sick Y By carrying enough virus to test positive, that means you are also reducing the risk of passing the virus from one vaccinated person to others.
The results of another recent study, not yet published, appear to show an even greater advantage for fully vaccinated people in Israel. Based on data analyzed by Israel’s Ministry of Health, Reuters reported Last Thursday, the risk of infection was reduced by 89% in people who received two doses of the Pfizer / BioNTech vaccine.
In the United States, a preliminary study published Last week researchers at the Mayo Clinic noted similar benefits for the Moderna vaccine. They looked at workers at the Mayo Clinic and associated healthcare facilities who had received the first dose of an mRNA vaccine at least 36 days earlier. Compared to their unvaccinated colleagues, workers were 89% less likely to test positive for COVID-19 after receiving both doses.
Many experts have been cautious in stating that covid-19 vaccines will reduce transmission, arguing that the data was simply not yet available to know for sure. But other experts have argument that it would be very unusual for an effective vaccine to prevent disease to have no effect on reducing transmission and that it is not helpful leave people worried about an unlikely outcome. In any case, the evidence of these and other studies It should be reassuring for everyone.
More research will continue to understand how effective mRNA vaccines are in preventing transmission. Other vaccines are based on different technologies, and some are less effective than mRNA vaccines in preventing disease, so they will need to be studied closely as well. And the spread of new coronavirus variants can complicate matters, as at least some vaccines have been shown to be less effective against certain variants.
All that said, this is certainly good news if you expect the pandemic to end as quickly as possible. Vaccines that prevent the disease and transmission of Covid-19 will only make it more difficult for the coronavirus to spread as more people are vaccinated, and should speed up the time it will take for life to return to something close to normal.