Can people vaccinated against COVID-19 transmit the virus?

One of the most common questions around the vaccine is whether it can prevent you from spreading the virus to other people.

Doctor applying a vaccine to a patient

According to the information provided by experts; the danger of transmitting the virus despite having the vaccine is low. Photo: Freepik

LatinAmerican Post | Moisés Campos

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Leer en español: ¿Las personas vacunadas contra el COVID-19 pueden transmitir el virus?

According to the information provided by experts; the danger of transmitting the virus despite having the vaccine is low. The possibility is present, however, the magnitude of its risk is still being studied. The vaccines that are currently being applied are effective in preventing the severity of the COVID-19 outbreak in humans.

Despite its effectiveness, there is also the possibility of transmitting the virus in immunized people, who after being infected could show no apparent symptoms. Scientists say that the COVID-19 vaccine can also reduce transmission in these people.

Experts evaluate vaccine efficacy

According to statements published in the newspaper, Dr. Robert Gallo, an expert in virology at the University of Maryland School of Medicine, explained that people who receive these vaccines have greater resistance, even in infected people the chances of transmission of the virus are greatly reduced. Gallo affirmed that it is necessary to remain prudent still, he says; that the vaccine is important, but it is not a solution that will eradicate the virus in a short time.

On the other hand, the United States proposes the study of the efficiency of vaccines against COVID-19 in university students, through the application of daily tests.

There are other reasons that can interfere with the transmission of the virus, such as the existence of vaccines, or the number of COVID-19 outbreaks in each region. As published on, Dr. Laraine Lynn Washer, an infectologist at the University of Michigan, stated that vaccines should have all or nothing effectiveness, but the results are specific.

Also read: The coronavirus could originate in an exotic animal farm according to the WHO

Does vaccination protect fully against infection?

No, people who have the COVID-19 vaccine can still get infections after the administered dose, but the chances of this happening are reduced, making the severity almost nil.

Given the thought that vaccines are a shield over health, to prevent infection and transmission of the virus, vaccinated people are actually protected, but they are not kept 100% free from infections.

As published on the page about COVID-19, the immune system of human beings is different in each individual, for this reason, a vaccine does not have the same percentage of effectiveness in all cases. Only 95% of people who have it are likely not sick.

The COVID-19 vaccine does not prevent the virus fully, but it strengthens the immune system against infections. In case people have a protected immune system or if the disease worsens, they will show a greater advantage compared to the unvaccinated.

Relationship of infection with transmission

The virus transmission process occurs when a sufficient number of virus particles pass to another healthy person. Anyone who has COVID-19 can transmit it to others, the vaccine reduces these chances by reducing the particles that cause the spread.

This means that the vaccine does not have enough power to prevent the coronavirus disease, but it is capable of greatly reducing infectious cells in the nasal passages, while reducing the duration of the virus in the body.

According to the same source at, a recent study by Israeli scientists, which has yet to be reviewed by other researchers, analyzed samples of infections in 2,900 people, looking for traces of COVID-19 to compare the infection among vaccinated people. and the unvaccinated.

Most vaccinated people had not been diagnosed with COVID-19, yet they remained infected with a quarter of the virus in their body, compared to unvaccinated people who had a higher amount.

Scientists do not know the limit of COVID-19, since recent vaccines are not fully effective in fighting the infection. For this reason, they encourage the use of masks and social distancing, even among the vaccinated.

In recent months, new variants of the coronavirus have emerged, and according to experts, vaccines are less capable against some strains. In cases of the South African-native strain, COVID-19 vaccines have approximately 85% protection against the severity of the disease.

Transmission of the virus after the vaccine

In the best of cases despite the application of vaccines against COVID-19, mild and moderate maintain up to 60% immune protection, compared to people who have not been vaccinated.

In it is explained that even 40% of those vaccinated will still present a high infection picture in their bodies to suffer a moderate infection. If vaccinated people have more infectious cells to transmit the virus, the chances of transmission will be greater with the new strains of COVID-19.

If all proceeds successfully, current vaccines will reduce the virus and its transmission. This means that they would lower the rates of cases and deaths from the disease.

However, although many people have already injected the vaccine, due to the emergence of new variants, the risk of transmission of the virus has not been completely eradicated, even if they are vaccinated.

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