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Can people vaccinated against COVID-19 still transmit the coronavirus?

When the U.S. Centers for Disease Control and Prevention changed their mask-wearing guidelines on May 13, 2021, many Americans were a little confused. Anyone who is fully vaccinated can now participate in indoor and outdoor activities. whether big or small without wearing a mask or keeping distance

Anthony Fauci, chief medical adviser to President Biden, said the new approach “Based on the evolution of science” and “acts as an incentive” for nearly two-thirds of Americans who are not fully vaccinated to continue shooting.

But some people cannot be vaccinated due to environmental conditions. other people with weakened immune systems from cancer or medical treatment May not be fully protected from vaccination. Children ages 1

2 to 15 are eligible for the vaccine. Pfizer-BioNTech As of May 10, 2021, the COVID-19 vaccine has not been approved for nearly 50 million children in the United States under the age of 12.

As restrictions are lifted and people start leaving masks at home, some people are worried: Can you get COVID-19 from someone who’s been vaccinated?

Vaccines do not always prevent infection.

Researchers hope to design a safe COVID-19 vaccine that will prevent at least half of vaccinated people from developing symptoms of COVID-19.

Fortunately, the vaccine has far exceeded expectations. For example, in the 6.5 million Israeli population aged 16 and over, the Pfizer–BioNTech mRNA COVID-19 vaccine was 95.3% effective after both injections. within two months Among 4.7 million fully vaccinated people, detectable infections were 30 times lower. Similarly, in California and Texas, only 0.05% of health care workers were fully vaccinated. who tested positive for COVID-19

Vaccine developers often hope that In addition to preventing disease their vaccine will achieve “Immune to sterilization,” where vaccination prevents pathogens from entering the body at all. This sterile immunity means that the vaccinated person does not contract the virus and does not transmit it further. It is not necessary to prevent germs from spreading to vaccinated individuals.

for example The Salk polio vaccine does not completely stop the growth of the polio virus in the human gut. But it is extremely effective in preventing crippling diseases because it activates antibodies that prevent the virus from infecting the brain and spinal cord. A good vaccine provides effective and durable training for the immune system. So when the pathogens that really cause disease are found is ready to respond most appropriately.

When it comes to COVID-19, immunoscientists are still searching for what they call The “protection correlation,” a factor that predicts how protected a person is from coronavirus, researchers believe. “Neutralizing antibodies” in the right amount. which is the kind that not only catches viruses but also prevents infection from virus This is enough to prevent re-infection. Scientists are still evaluating the tolerance of immunity at the COVID-19 vaccine. It is available and works anywhere in the body.

Can vaccinated people spread coronavirus?

Immunologists expect that vaccines that protect against the virus will reduce transmission of the virus after vaccination, but it is actually difficult to know for sure if people vaccinated are not infectious.

COVID-19 poses a special challenge. This is because people who are asymptomatic and pre-existing infections can spread the infection. And inadequate exposure monitoring and testing means people without symptoms are rarely detected. Some scientists estimate that the number of asymptomatic COVID-19 cases in the overall population could be 3 to 20 times higher than the number of confirmed cases. 19 In people who have no symptoms or have experienced a very mild disease It may account for up to 86% of all infections, although other studies contradict high estimates.

In one study, the CDC tested volunteer health care workers and other frontline workers. in eight US locations for SARS-CoV-2 infection weekly for three months. regardless of symptoms or vaccination status. Researchers have found that fully vaccinated participants were more likely to contract COVID-19. It was 25 times less positive than those who were not vaccinated. Such findings indicate that if the vaccinated person was well protected from infection, They are also unlikely to spread the virus. But if the infection is not tracked to track the outbreak in a large population. It is impossible to know whether this assumption is true or not.

What we know for sure is that If someone is sick with COVID-19 after vaccination in the so-called “Invasive infection” symptoms will be more severe. The results showed that People who have been diagnosed with COVID-19 after receiving the first vaccine have a lower viral load than unvaccinated people who test positive Researchers believe that lower viral loads indicate that vaccinated people who contract the virus will become less infected because they will have much less virus that can spread to others.

A pre-printed study, which has not been reviewed by peers, shows that the Moderna mRNA COVID-19 vaccine can produce antibodies that fight coronavirus in oral and nasal fluids. Since SARS-CoV-2 is where SARS-CoV-2 comes in, the antibodies in the mouth and nose should prevent the virus from entering the body, thus providing an effective “sterilization immunity.” This also means that the vaccinated person may not spread the virus through respiratory droplets.

These evidence are promising. But without further study Scientists still cannot conclude that the COVID-19 vaccine It can really prevent the spread of all infections. A study that seeks to directly answer this question through contact tracing has just begun: Researchers will track COVID-19 infections among vaccinated and unvaccinated volunteers and their close contacts.

Prevention and protection go hand in hand.

Vaccines slow the spread of infectious diseases by breaking the chain of infection. Eventually, those infected will have fewer and fewer unprotected people to spread the virus. This is how vaccines boost herd immunity – those who are weak and not yet immunized are surrounded by a “herd” of people who have been immune due to previous vaccinations or infections. But the study showed that for biological and social reasons Vaccination alone is unlikely to achieve herd immunity against COVID-19 and full coronavirus control.

In fact, vaccination alone can take a long time to eradicate diseases. Even diseases that are almost “eradicated” such as chickenpox, measles and whooping cough can come back with reduced immunity and lower vaccine rates.

The recent outbreak of infection among the vaccinated New York Yankees shows that not only people vaccinated can get infected. But it may also spread the coronavirus to close contacts. Highly tested groups, such as professional sports teams, highlight the fact that mild and asymptomatic infections among the general vaccinated population may be more common than reported. A similar outbreak in Singapore airport staff showed that even among those who had been fully vaccinated, Newer and more infected species can spread quickly.

The CDC’s relaxed approach to masking is meant to reassure people vaccinated that they are safe from serious illness. and they are But the picture will be less clear for unvaccinated people who interact with them. until they are immune to COVID-19 nearby the herd And there is clear evidence accumulating that people vaccinated do not transmit the virus. I and many epidemiologists believe that it is better to avoid situations where there is a possibility of infection. Vaccination, coupled with continued masking and social distancing, remains an effective way to stay safer.

Sanjay Mishra, Project Coordinator and Personnel Scientist Vanderbilt University Medical Center Vanderbilt University

This article is republished from The Conversation under a Creative Commons license.

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