COVID-19 vaccine's impact on transmission remains unknown; experts urge masks, social distancing

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Posted at 3:23 PM, Jan 25, 2021

As more and more people around the world receive the COVID-19 vaccine, health experts are warning that there is a chance vaccinated people could still transmit the coronavirus to others, even if it doesn’t affect them. Reminding everyone to keep wearing masks and social distance even if they are vaccinated.

"Even after you have had both doses of the vaccine you may still give COVID to someone else and the chains of transmission will then continue,” wrote Professor Jonathan Van-Tam, England’s deputy chief medical officer in an article published Sunday in the Telegraph.

"If you change your behaviour you could still be spreading the virus, keeping the number of cases high and putting others in danger who also need their vaccine but are further down the queue,” he continued.

Scientists “do not know the impact of the vaccine on transmission,” Prof. Van-Tam wrote, which echoes similar statements from health experts in the U.S.

“Experts need to understand more about the protection that COVID-19 vaccines provide before deciding to change recommendations on steps everyone should take to slow the spread of the virus that causes COVID-19,” the Centers for Disease Control and Prevention notes in its vaccination FAQ.

The CDC reported recently that people with no symptoms of COVID-19 transmit more than half of all COVID-19 cases in this country. And there is no strong evidence showing the impact the vaccines have on transmission, just on their effectiveness in preventing symptoms.

Another reminder that stay-at-home orders, mask requirements and social distancing guidance will not go away overnight, and that leaders will monitor the level of community spread before lifting restrictions, the CDC states.

There are also other reasons people who receive a vaccine should continue to wear a mask and social distance.

The Pfizer and Moderna vaccine, the two granted emergency use authorization in the U.S., are both more than 90% effective. And while that is incredible, it’s not 100%. A vaccinated person can still contract the coronavirus and have symptoms.

Both vaccines also take time to become that effective, it is not immediate, more like a few to several weeks. It is possible for someone to be exposed to the virus and develop symptoms before the vaccine has had a chance to build up strength in the body.