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Don’t believe me, the experts have reached a consensus: thousands of people have been vaccinated against the new corona, but they can still carry the virus and spread it to others. Although these people themselves have been well protected, they are still contagious. This means that even if people are vaccinated, they must wear masks and maintain social distance to protect those around them.
Dr. Janet Besman, a public health expert at the University of Washington, said: “We still need to understand the impact of vaccination on infectivity to protect those with whom I have been in contact, not just myself. “
Vaccine development is proceeding rapidly and uncertainty will continue. Under normal circumstances, vaccine trials will observe subjects for a considerable period of time before being used in large quantities. This may not only understand the subject’s disease, but also the degree of contagion remaining. To be sure, the various corona vaccine candidates for new corona have controlled the spread of the virus to some extent, but it is still difficult to say to what extent.
The scientific principles behind this contradiction are not really complicated. The Pfizer and Moderna vaccines are injected into deep muscles to provide so-called “systemic immunity.” But there are still some areas that will be overlooked (such as the nasal mucosa passage) and the virus can still reproduce relatively freely. Even if the host is not infected, the new coronavirus can be transmitted by coughing and sneezing, and there is no difference between the route of transmission from the infected person.
Joshua Mishaw, epidemiologist at KFF (formerly known as the Kaiser Family Foundation), said: “The role of systemic immunity is similar to building security. Having mucosal immunity is like hiring a bodyguard to watch the door. virus attack “.
Researchers can take several months to determine the location of the virus’s “bodyguard.” Because this process needs to monitor people who have been vaccinated, it takes a while. Besman said that research in vaccinated populations (such as college students) with “high levels of mixing and high risk of transmission” can provide data on more rapid transmission after vaccination. Mishaw expects key communication research to take place in “the coming weeks and months.”
Regarding the question of the transmissibility of vaccinators, the answer can also be obtained through ongoing vaccine trials. Although the Pfizer and Moderna vaccines have been approved for emergency use by healthcare agencies such as the US Food and Drug Administration (FDA), drug manufacturers still continue to conduct standard trials. Upon completion of the trial, permanent approval will be issued.
A Pfizer spokesperson said: “Our trials will continue to determine the overall protective ability of the vaccine.” The ability of the virus to spread after vaccination will also be included in the trial.
However, before long-term test data and other experimental results are published, only by measuring the spread of the new coronavirus in people with high levels of vaccination can the geometry of infectivity after vaccination be clarified. If the spread of the virus slows down, it indicates that vaccination has reduced infectivity. But even in developed countries where the vaccine is first launched, high levels of vaccination are not expected to be reached until mid to late 2021. The time taken for this method can take more than half a year.
According to the US Food and Drug Administration, most vaccines prevent disease while reducing the transmission capacity of vaccinators. We have reason to be optimistic: the current wave of new corona vaccines will be the same. In particular, Moderna’s vaccine trial showed that the number of asymptomatic infections has decreased through nasal swab testing, which may indicate that the transmission potency after vaccination has decreased. Dr. Eric Topol of the Scripps Research Translational Institute said that these findings are not yet conclusive, but in fact it is possible that “the transmissibility after vaccination is reduced.”
However, before more conclusive data comes in, the information from the health department is pretty clear: even if you’ve been vaccinated, don’t forget to wear a mask. (Chinese Fortune Network)
Compiler: Yang Eryi
It’s surprising, but experts agree: the tens of thousands of people who are being vaccinated against the coronavirus right now can still carry and transmit the SARS-CoV-2 virus to other people, despite being well protected against it. symptoms of COVID-19. themselves. That means they must still wear masks and practice social distancing to protect those around them.
“We have yet to learn how much vaccination affects infectivity, thereby producing protection for those I come in contact with, not just me, when I receive a vaccine,” says Dr. Janet Baseman, a public health expert at the University of Washington.
This uncertainty is a consequence of the extremely rapid vaccine development process. Typically, a vaccine trial would observe vaccine recipients for a longer period of time, showing not just whether they got sick, but spread the contagion, before a vaccine entered widespread use. While the various coronavirus vaccine candidates are likely to provide at least some reduction in transmission, it is too early to know for sure or to what degree.
The science behind this apparent contradiction is relatively straightforward. Vaccines like those from Pfizer and Moderna are injected into deep muscle and provide so-called systemic immunity. But they can still leave areas, particularly the nasal mucous passages, where the virus is relatively free to multiply. Even without making the host sick, that virus can potentially be spread through coughing or sneezing, just as it is transmitted by a person with a full-blown coronavirus infection.
“Having systemic immunity is like having a security guard somewhere in the building,” says Joshua Michaud, epidemiologist at KFF (formerly the Kaiser Family Foundation). “Having mucosal immunity is like having a security guard at the door, ready to deal with the incoming virus.”
Investigators could take months to determine where that viral security guard is stationed, because it requires monitoring people who have already been vaccinated. According to Baseman, a study focused on vaccinated people “with high levels of mixing and high risk of transmission,” such as college students, could provide faster data on post-vaccination transmission. Michaud expects specific transmission studies to be conducted in “the next few weeks and months.”
Understanding the question will also come through ongoing vaccine trials. Although the Pfizer and Moderna vaccines have been approved for emergency use by health authorities such as the US FDA, drug manufacturers continue with standard trials that should lead to permanent approval.
“Our trial will continue to determine the full protection and potential of the vaccine,” including transmission after vaccination, according to a Pfizer spokesperson.
But until long-term trial data or other experimental results are published, post-vaccine infectivity will become clear only by measuring the spread of the coronavirus through populations with high levels of vaccination. If the spread is slowed, it will show that vaccination reduces transmission. But much of 2021 is expected to reach high levels of vaccination even in countries that are at the front of the line, so that approach could take the better part of a year.
According to the FDA, most vaccines that protect against viral diseases also reduce the viral transmission of those who are vaccinated, and there is reason for optimism that the current wave of COVID vaccines will as well. Most notably, Moderna’s vaccine trial showed some reduction in asymptomatic infections measured through nasal swabs, which could suggest a reduction in transmission after vaccination. Dr. Eric Topol of the Scripps Research Translational Institute has described those findings as inconclusive, but promising on the question of post-vaccine transmission.
However, until more conclusive data comes in, the message from health authorities is clear: even after you’ve been vaccinated, don’t throw away the mask.
