Vaccinated people are far less likely to transmit the virus to others. Recent CDC data shows that vaccines cut transmission of the virus by around 80% as early as 2 weeks after the first dose. But nothing in life is 100%, so there is still a small risk that you can spread the virus to the people around even after you’ve been vaccinated. That’s why until we have reached herd immunity, it is important to continue the public health practices we have used during the pandemic: mask up, social distance, and wash our hands.

There is a growing body of evidence that suggests that fully vaccinated people are less likely to transmit COVID-19. Recent data from Israel suggest that people who were vaccinated with the Pfizer-BioNTech vaccine who developed COVID-19 had a four-fold lower viral load than unvaccinated people. While this is only observational data, we know that viral load has been a key driver of transmission, as seen with the UK variant.

It seems almost like a dream come true, but recent studies in Israel and among healthcare workers suggest that fully vaccinated people are much less likely to become infected or transmit the virus for at least several months after vaccination. It may not hold for every person who’s vaccinated, and may vary with the vaccine, but that’s still a triumph. It means that unvaccinated people can feel much safer around vaccinated people. If they get infected, it’s very likely they caught the virus from an unvaccinated person. It’s a good reason to get vaccinated as soon as possible. Having vaccines makes an enormous difference.

We shouldn’t take this outcome for granted. Preventing infection or transmission is a high bar for a vaccine to meet, and it may be more the exception than the rule.

We’re still in a race with the virus. Variants of the virus evolve as the virus reproduces in infected people and is transmitted. The more virus transmission, the greater risk of new variants, so we want to reduce the risk of new variants by stopping or slowing down virus transmission as much as we can. The masks and other precautions are intended to reduce transmission. If the vaccine drastically reduces the amount of virus circulating, it will slow down the appearance of new variants, along with its other benefits. We worry that eventually variants may evolve for which the vaccine no longer protects, with an ensuing ‘arms race,’ before we get enough people vaccinated. This is the familiar situation with the seasonal flu. These variants can arise anywhere in the world where the virus is actively circulating, like the South African and Brazilian variants, so that means controlling the virus everywhere in the world – vaccinating worldwide.

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Multiple studies with a variety of vaccines—influenza, hepatitis B, typhoid and pneumonia—have shown that stress, depression, loneliness, and poor health behaviors can impair the immune system’s response to vaccines, and this effect may be greatest in vulnerable groups like the elderly. These risk factors can slow the development of a protective antibody response and may lead to earlier erosion of vaccine-produced antibodies. Obviously reducing stress and depression prior to vaccination could be helpful but may be difficult; however, the research also points to several relatively easy ways to help maximize vaccine responses in the short term. Getting a good night’s sleep prior to vaccination and exercising vigorously within 24 hours before receiving the vaccine can boost immune system responsiveness. In fact, one study showed that a 25-minute eccentric arm exercise protocol that targeted the muscle at the site of injection, performed six hours prior to an influenza virus vaccination, enhanced vaccine responses compared to those who rested quietly. Other studies show that a less sedentary and more active lifestyle, better nutrition, and low to moderate alcohol use can make a difference in immune system responsiveness to vaccination.