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COVID-19 Vaccination doesn’t mean normal life restored
COVID-19 Vaccination doesn’t mean normal life restored. The U.S. Food and Drug Administration approved the emergency use authorization application for the COVID-19 vaccine jointly developed by Pfizer Pharmaceuticals Co., Ltd. and German Biotech on December 11. This is the first new coronavirus vaccine approved for emergency use in the United States, and is allowed to be used for people 16 years and older.
International cooperation on COVID-19 pandemic
In the global COVID-19 vaccine research and development competition, several manufacturers have successively announced that their vaccines have achieved success in late-stage clinical trials. At present, the U.S. Food and Drug Administration (FDA) has approved emergency use authorization for Pfizer and BioNTech’s COVID-19 vaccine, and Moderna’s vaccine is under consideration for emergency use authorization. However, there are still some important issues of general concern about how these vaccines will work once they are used.
Although people who receive the COVID-19 vaccine, especially those at high risk who are most likely to develop complications and cause serious illness and death, can be protected quickly, the vaccination may still not indicate that people can return to normal life.
The official website of the US “Science News” magazine uses a question and answer format to discuss this:
Q: If vaccinated, can the vaccinated person still infect other people?
Answer: Maybe. So far, none of the vaccines tested is 100% effective, so some people who have been vaccinated may still be infected with the new coronavirus.
Moreover, neither Pfizer nor Moderna’s vaccine trials have tested whether this vaccine can prevent people from contracting the virus. Instead, these tests look at whether people can avoid symptoms of disease. This means that it is not clear whether people who have been vaccinated will still have asymptomatic infections and thus still be able to spread the virus to others.
In these two trials, some vaccinated people did develop new coronavirus disease, but the condition was not as good as those who took placebo. In the Pfizer study, 1 vaccinee was severely ill, compared to 9 in the placebo group. None of the people who had been vaccinated with the Moderna vaccine became seriously ill, and 30 people developed serious illnesses after receiving a placebo.
In another trial, AstraZeneca and the University of Oxford reported that they found fewer asymptomatic cases in vaccinated people than in the control group, which may indicate some protection against infection and disease. However, it remains to be seen how these vaccines actually affect transmission.
Q: So what are these vaccines for?
Answer: These vaccines seem to reduce the likelihood of symptoms and the severity of the disease after infection. This may be of great help in preventing death and reducing some of the long-term side effects of the new coronavirus. These include heart and lung problems that some people experience after the onset of the disease.
It is true that the ideal vaccine can reduce the risk of transmission, but not all. For example, influenza vaccines may not prevent all infections, especially when these vaccines do not exactly match the virus strains that circulate each year. At other times, vaccination can reduce the chance of infection, but it cannot completely eliminate it. The immune protection established by the perfect match of the vaccine will slip due to the rapid mutation of the influenza virus. But even an imperfect vaccine can reduce the condition of flu.
Q: After vaccination, do people still need to wear masks and maintain social distance?
Answer: Yes. It takes several weeks to establish vaccine-induced antibodies and other immune defense systems. Both Pfizer and Moderna vaccines require booster doses 21 to 28 days after the first dose. Therefore, it will take at least one month for the full protection provided by the vaccine to develop.
Since vaccines do not work well at this stage, and it is not clear whether they can prevent infection, people who are vaccinated are likely to contract the virus and pass it on to others.
Although vaccines may help control the COVID-19 epidemic, people must understand that this is not a magician’s wand. This does not mean that people can suddenly abandon all other activities that are critical to reducing infection rates. In other words, people still need to wear masks, maintain social distancing, wash hands and avoid big gatherings, especially indoors. In addition, it also takes time to vaccinate everyone, and other safety measures still need to be taken before the way vaccines prevent transmission becomes clear.
Q: Are these vaccines safe?
Answer: So far, they seem to be safe. Most vaccine side effects occur within the first few weeks to several months after obtaining the vaccine, which is why the FDA requires vaccine manufacturers to have two months of safety data before applying for emergency use authorization.
Data collected in clinical trials indicate that the side effects of the vaccine include fever, headache, arm soreness, redness at the injection site and feeling tired. For vaccines approved for other diseases, such side effects are also common.
Even after the vaccine is released to the public, government regulators, healthcare organizations, and manufacturers will continue to collect safety data.
Q: When can groups such as children or pregnant women be vaccinated?
Answer: No vaccine has been tested for children under 12 years old or pregnant women, so these two groups may be at the back of the vaccination queue. In particular, women of childbearing age account for a large proportion of health care and front-line workers. Therefore, vaccines will not be provided to everyone until they are provided to pregnant women.
Researchers have been waiting for data from animal studies on how vaccines affect pregnant women’s reproduction and development. Some companies are now near the end of such studies and may soon start testing vaccines in pregnant women.
For children, researchers are still waiting to discover the effectiveness of the vaccine. Since at least the first vaccines are highly effective in preventing symptoms, this makes it easier for manufacturers to conduct children’s trials.
Pfizer has already tested its vaccine in teenagers over the age of 12, and Moderna also plans to test it soon. This is a typical vaccine testing process, starting with healthy adults, then teenagers, and up to young children.
Vaccine experts said that it is expected that before the start of the fall semester of 2021, there will be vaccines for children 12 years and older. At that time, younger children will also have vaccines.
Q: Can these vaccines help us gain herd immunity?
A: Scientists are still studying how many people must be immune to the virus in order to contain the outbreak of susceptible hosts and end the pandemic. Although how much vaccine is needed to achieve this is still unclear, most experts estimate that this number will account for 60% to 80% of the population, depending on the efficacy of the vaccine.
If vaccines play the greatest role in preventing disease and transmission, it is enough to vaccinate enough people to accurately reach the herd immunity threshold. But if the vaccine is less effective, more people need to be vaccinated to solve the potential gap in immunity.
Generally, certain vaccines are more effective in reducing the severity of the disease than reducing transmission. As mentioned above, it is still unclear how vaccines such as Pfizer and Moderna affect transmission. If these vaccines cannot prevent transmission at all, herd immunity cannot be achieved through vaccination. But the following situation is extremely unlikely: by reducing the severity of the disease, the vaccine may reduce transmission by reducing the number of days a person is infected with the virus. Currently, scientists are waiting for more data.
Even if the vaccine is indeed effective in reducing transmission, a fair distribution of vaccines is still required to achieve herd immunity on a global scale, which will be challenging in view of the current logistics requirements for vaccine transportation and storage. If people in poor or rural areas do not have access to vaccines, then outbreaks in these areas may persist, and if the problem spreads, stopping the pandemic may become empty talk.