Can a person with a vaccine still get the coronavirus?

1. Why is this important?

Although the vaccine provides a great insurance for people against becoming ill with Covid, which is sometimes fatal, if they could still be quietly infected with SARS-CoV-2, it could to give them, potentially ill people who are not immune. Those who are infected but do not develop symptoms are responsible for 24% of transmission, one study has estimated. The more SARS-CoV-2 circulates, the more the virus has a chance to circulate in ways that increase its ability to spread, infect and kill humans, and bypass the immunity provided by the virus. existing vaccines or past infections. Already, variants of the virus have emerged that appear to be more dangerous. Also, with the use of vaccines for so-called herd protection, when an entire community is protected even though not everyone has been vaccinated, vaccines that prevent transmission are required.

2. Do vaccines not stop infection and therefore give them?

Some do and some don’t. The gold standard in vaccines is to prevent infection as well as disease – providing sterilizing immunity. But it is not always accomplished. The measles vaccine, for example, is given; the one is not for hepatitis B.

3. Do Covid vaccines need to prevent infection to stop the spread?

Not necessary. To the extent that a vaccine prevents infection, it also prevents the spread. But he can do the last one without doing the first one. Because SARS-CoV-2 is transmitted through the respiratory tract from the throat and nose of an infected person, a vaccine that reduces the duration of the infection, the level of virus in the respiratory tract (the viral load), or its frequency in which an infected person may cough has reduced the likelihood of transmission to others.

4. Why do we not know for sure how well Covid vaccines prevent infection and transmission?

The tests testing the vaccines were not set up to answer these questions at first. Instead, they were designed to test the more pressing issue of whether vaccines would stop people from becoming ill and overcoming medical systems. To investigate that question, researchers typically administered the experimental vaccine to one group of volunteers and another placebo to another group of similar size. After the total number of volunteers with Covid symptoms confirmed in the test reached a predetermined level, researchers compared the number in each group to see if those who received the vaccine were significantly more better than those who received the placebo. For the inoculations that have worked, the vaccine groups have been anywhere from 50% to 95% fewer cases of illness, figures known as vaccine efficacy levels.

5. Why not check out volunteers for asymptomatic diseases as well?

That’s a more complicated task because the only way to experience asymptomatic diseases is to regularly test volunteers, who can count into tens of thousands in an effectiveness test. However, there are about two dozen studies in which the vaccines tested to prevent infection do just that.

6. What did they find?

The results so far are preliminary. The most widely released data relates to the vaccine produced by AstraZeneca Plc. In a UK study, volunteers are screened for SARS-CoV-2 infections using weekly self-administered nose and throat swabs. According to results from December 7, after a single dose, the vaccinated group had 67% fewer advanced swabs than the placebo group, suggesting that the vaccine cuts down on infections as well as disease. Moderna Inc. reported. similar results from people who had received a single dose of the vaccine since November. An earlier study of the Moderna vaccine in monkeys suggested that it could reduce, if not completely stop, the spread of the virus.

7. What other evidence do we have?

Since vaccines were approved by regulators, studies have compared results for those that have been and have not been included outside of clinical trials. These studies are not as reliable as those in which participants are randomly assigned to a vaccine or placebo group, but when performed well they provide important evidence. In particular:

A study published Feb. 24 of nearly 1.2 million people in Israel, which has imported a higher percentage of its population than any other country, estimated that the Pfizer- BioNTech is 92% effective in preventing all infections. The research team warned that their analysis may not have been able to accurately capture the effectiveness of the vaccine against all asymptomatic diseases because the study subjects were not routinely tested for the virus.

An earlier study in Israel suggested that the same vaccine cuts the risk of infection by 89%, although some scientists say the report’s approach may have had too much of an impact.

Other data from Israel suggest that the Pfizer-BioNTech vaccine could reduce transmission even if it does not prevent infection. After more than 75% of people aged 60 and over received a single dose of vaccine and only 25% of those between the ages of 40 and 60, researchers from Israel’s largest coronavirus testing laboratory looked at the their data. For those who tested positive for SARS-CoV-2, there was a significant difference between the two age groups in the average number of viruses detected in test swabs. The researchers estimated that the vaccine reduces the viral load by 1.6 to 20 times in individuals despite the burn. Another study in Israel found that after people suffered from vaccination, the vaccine reduced their viral load by four times.

Initial data from the UK, the first western country to apply Covid vaccines, show that the inoculation from Pfizer Inc. and BioNTech reduce the risk of infection by more than 70% after a single dose and 85% after a second dose, according to Public Health England.

8. When will we know more?

As the vaccine becomes more widely available, researchers should be able to identify the effect on infection and transmission patterns, although it may be difficult to differentiate the effect of inoculations from the effect of measures such as locks and masonry orders. Completion of the test vaccine tests for asymptomatic diseases will provide additional information. Two trials are expected to be completed in April. However, one vaccine from Sinovac Biotech Ltd. in China, which has a reported efficacy rate as low as 50% against symptomatic disease. The other trials fire at the bullet of the Russian Gamaleya Research Institute, which had an efficacy against symptoms of 92% in clinical trials, but it is a small study. September should end major trials of highly effective vaccines. Results are not expected for the pictures that have been as effective in preventing disease (95%), from Moderna and Pfizer-BioNTech, to October 2022 and January 2023, respectively.

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