Nine vaccines are effective in protecting people against the development of symptoms of Covid-19, the disease that can result from infection with the SARS-CoV-2 virus. However, it is not yet known how well the vaccine prevents people from getting an asymptomatic infection or transmitting the virus to others. Preliminary signs indicate that they do at least some of both.
Live Updates: Coronavirus Pandemic
1. Why is it important?
Although vaccinated, humans offer significant health insurance with Covid, which is sometimes fatal. So far, there is no assurance that they will not quietly become infected with SARS-CoV-2 and pass it on, and people who are not immune may become ill. . Those who are infected but never develop symptoms are responsible for 24% of the transmission, according to one study.
The more SARS-CoV-2 circulates, the more likely the virus is to mutate in a way that improves the ability to spread, kill and kill humans, and the immunity that existing vaccines or an infection have in the past offers, to evade. Variants of the virus that already appear more dangerous have already emerged. To use vaccination to bring about the so-called herd immunity, when an entire community is protected, although not everyone is vaccinated, vaccination is also needed that can prevent transmission.
2. Do the vaccines not stop the infection and thus the transmission?
Some do and others do not. The gold standard in vaccination is to stop infection and disease – it provides so-called sterilization immunity. But this is not always achieved. The measles vaccine provides it, for example; the one for hepatitis B.
Coronavirus Pandemic: Full Coverage
3. Should Covid vaccines prevent infection from stopping transmission?
Not necessarily. To the extent that a vaccine infection occurs, it also prevents the transmission going forward. But it can do the latter without doing the former. Because SARS-CoV-2 spreads through respiratory particles from the throat and nose of an infected person, a vaccine that reduces the duration of the infection, the amount of virus in the airways (the virus load) or how often an infected person cough. reduces the likelihood of it being passed on to others.
4. Why do we not know if Covid vaccines prevent infection and transmission?
The trials testing the vaccines were not set up to answer the questions first. Rather, they are designed to initially determine the more urgent matter of whether vaccines will prevent people from becoming ill and overwhelming medical systems. To investigate the question, researchers usually gave the experimental vaccine to one group of volunteers and another group of equal size a placebo. After the total number of volunteers with confirmed Covid symptoms in the trial reached a predetermined level, researchers compared the number in each group to determine whether those who received the vaccine performed significantly better than those who received the placebo. has. For the vaccinations that worked, the vaccine groups had approximately 50% to 95% fewer disease cases, which is referred to as the efficacy rate of the vaccines.
5. Why do volunteers also not look for asymptomatic infections?
This is a more complicated undertaking, as the only way to know about asymptomatic infections is to test volunteers regularly, which can count the tens of thousands in an efficiency test. Nevertheless, about two dozen studies are being done regarding vaccination that are proven to prevent disease.
6. What did they find?
The results so far are preliminary. The most extensive data released relates to the vaccine made by AstraZeneca Plc. In a study in the United Kingdom, volunteers were monitored for SARS-CoV-2 infections using weekly, self-administered nasal and throat swabs. According to the results from December 7, the group that received the vaccine after a single dose had 67% less positive swabs than the placebo group, indicating that the vaccine reduces infection as well as diseases. Earlier, Moderna Inc. similar results were reported from people who received a single dose of the vaccine from November.
7. What other evidence do we have?
Data from Israel, which vaccinated a higher percentage of its population than any other country, give indications that the vaccine used there is from Pfizer Inc. and BioNTech SE, can reduce transmission, even if it does not protect against infection. After more than 75% of people 60 years and older received one dose of vaccine and only 25% of those between the ages of 40 and 60 years old, researchers from Israel’s largest coronavirus testing laboratory looked at their data. For those who tested positive for SARS-CoV-2, there was a noticeable difference between the two age groups in the average amount of viruses found in the swabs. The researchers estimate that the vaccine reduces the viral load by 1.6 to 20 times in individuals who become infected despite the shot. In another study in Israel, following people who became infected after vaccination, the vaccine was found to quadruple their viral load. A study of Moderna’s Covid vaccine in monkeys has also suggested that it reduces the transmission of the virus, if not completely.
8. When will we know more?
As vaccination widens, researchers need to be able to distinguish the effect on infection and transmission patterns, although it can be difficult to distinguish the impact of vaccinations from measures such as locks and mask mandates. Completing the testing of vaccines for asymptomatic infections will provide additional information. Two trials are expected to be completed in April. One of these, however, is a vaccine from Sinovac Biotech Ltd. in China, which has a reported efficacy rate of as low as 50% against symptomatic diseases. The other is testing the Russian Gamaleya Research Institute, whose efficacy against symptoms was 92% in clinical trials, but this is a small study. In September, the substantial trials of highly effective vaccines should be completed. The results for the shots that proved most effective in preventing disease (95%), from Moderna and Pfizer-BioNTech, are not even expected in October 2022 and January 2023, respectively.
Live Updates: Coronavirus Pandemic
1. Why is it important?
Although vaccinated, humans offer significant health insurance with Covid, which is sometimes fatal. So far, there is no assurance that they will not quietly become infected with SARS-CoV-2 and pass it on, and people who are not immune may become ill. . Those who are infected but never develop symptoms are responsible for 24% of the transmission, according to one study.
The more SARS-CoV-2 circulates, the more likely the virus is to mutate in a way that improves the ability to spread, kill and kill humans, and the immunity that existing vaccines or an infection have in the past offers, to evade. Variants of the virus that already appear more dangerous have already emerged. To use vaccination to bring about the so-called herd immunity, when an entire community is protected, although not everyone is vaccinated, vaccination is also needed that can prevent transmission.
2. Do the vaccines not stop the infection and thus the transmission?
Some do and others do not. The gold standard in vaccination is to stop infection and disease – it provides so-called sterilization immunity. But this is not always achieved. The measles vaccine provides it, for example; the one for hepatitis B.
Coronavirus Pandemic: Full Coverage
3. Should Covid vaccines prevent infection from stopping transmission?
Not necessarily. To the extent that a vaccine infection occurs, it also prevents the transmission going forward. But it can do the latter without doing the former. Because SARS-CoV-2 spreads through respiratory particles from the throat and nose of an infected person, a vaccine that reduces the duration of the infection, the amount of virus in the airways (the virus load) or how often an infected person cough. reduces the likelihood of it being passed on to others.
4. Why do we not know if Covid vaccines prevent infection and transmission?
The trials testing the vaccines were not set up to answer the questions first. Rather, they are designed to initially determine the more urgent matter of whether vaccines will prevent people from becoming ill and overwhelming medical systems. To investigate the question, researchers usually gave the experimental vaccine to one group of volunteers and another group of equal size a placebo. After the total number of volunteers with confirmed Covid symptoms in the trial reached a predetermined level, researchers compared the number in each group to determine whether those who received the vaccine performed significantly better than those who received the placebo. has. For the vaccinations that worked, the vaccine groups had approximately 50% to 95% fewer disease cases, which is referred to as the efficacy rate of the vaccines.
5. Why do volunteers also not look for asymptomatic infections?
This is a more complicated undertaking, as the only way to know about asymptomatic infections is to test volunteers regularly, which can count the tens of thousands in an efficiency test. Nevertheless, about two dozen studies are being done regarding vaccination that are proven to prevent disease.
6. What did they find?
The results so far are preliminary. The most extensive data released relates to the vaccine made by AstraZeneca Plc. In a study in the United Kingdom, volunteers were monitored for SARS-CoV-2 infections using weekly, self-administered nasal and throat swabs. According to the results from December 7, the group that received the vaccine after a single dose had 67% less positive swabs than the placebo group, indicating that the vaccine reduces infection as well as diseases. Earlier, Moderna Inc. similar results were reported from people who received a single dose of the vaccine from November.
7. What other evidence do we have?
Data from Israel, which vaccinated a higher percentage of its population than any other country, give indications that the vaccine used there is from Pfizer Inc. and BioNTech SE, can reduce transmission, even if it does not protect against infection. After more than 75% of people 60 years and older received one dose of vaccine and only 25% of those between the ages of 40 and 60 years old, researchers from Israel’s largest coronavirus testing laboratory looked at their data. For those who tested positive for SARS-CoV-2, there was a noticeable difference between the two age groups in the average amount of viruses found in the swabs. The researchers estimate that the vaccine reduces the viral load by 1.6 to 20 times in individuals who become infected despite the shot. In another study in Israel, following people who became infected after vaccination, the vaccine was found to quadruple their viral load. A study of Moderna’s Covid vaccine in monkeys has also suggested that it reduces the transmission of the virus, if not completely.
8. When will we know more?
As vaccination widens, researchers need to be able to distinguish the effect on infection and transmission patterns, although it can be difficult to distinguish the impact of vaccinations from measures such as locks and mask mandates. Completing the testing of vaccines for asymptomatic infections will provide additional information. Two trials are expected to be completed in April. One of these, however, is a vaccine from Sinovac Biotech Ltd. in China, which has a reported efficacy rate of as low as 50% against symptomatic diseases. The other is testing the Russian Gamaleya Research Institute, whose efficacy against symptoms was 92% in clinical trials, but this is a small study. In September, the substantial trials of highly effective vaccines should be completed. The results for the shots that proved most effective in preventing disease (95%), from Moderna and Pfizer-BioNTech, are not even expected in October 2022 and January 2023, respectively.