[ad_1]
2. Strong immune response
Scientists testing the efficacy of vaccines usually focus on antibodies and their ability to prevent viruses from infecting cells. In laboratory experiments, they mixed the blood of a person who was infected or inoculated with cells into a petri dish to see if the antibodies in the blood could “neutralize” the virus. These experiments are easy to perform. According to Jennifer Dowd, an epidemiologist and demographer at Oxford University, antibodies “may be only a small part of the immune response in the body.”
Immune cells called T cells also help control infections. These cells cannot neutralize the virus, but they can find infected cells and destroy them. This helps prevent serious diseases. Data from the covid-19 population suggests that the T cell response should provide adequate protection for most SARS-CoV-2 variants.
3. When the vaccinated person is indeed infected, vaccination can prevent the worst consequences
The vaccine that can stop the infection is great. But Friedrich said: “The most important thing is to keep people away from the hospital, away from the ground.” And there is ample evidence that current vaccines can indeed do this.In South Africa, a dose of Johnson & Johnson vaccine Provides 85% protection Oppose hospitalizations and deaths related to covid-19. At that time, 95% of cases were caused by the B.1.351 variant. In israelAmong them, B.1.1.7 has become the main strain, and two doses of Pfizer provided 97% protection to prevent symptomatic covid-19 and covid-19-related hospitalization.
4. The same mutation keeps popping up
Once the virus enters the cell, it will begin to replicate. The more copies it makes, the greater the chance of random errors or mutations. Most of these replication errors are irrelevant. However, a few may make the virus worse. For example, a mutation in a spike protein called D614G appears to contribute to the spread of SARS-CoV-2. Another E484K may help the virus evade the body’s antibody response. If viruses carrying these favorable mutations are transmitted from one person to another, they can start to compete with viruses that lack them. This is the process of natural selection. This is how the more transmissible variant of B.1.1.7 became the main strain in the United States.
Taking SARS-CoV-2 as an example, mutations that improve the virus continue to appear all over the world. This phenomenon is called convergent evolution.Vaughn Cooper, an evolutionary biologist at the University of Pittsburgh, said: “We see the same combination develop over and over again.” Imagine a game of Tetris, Cooper wrote The latest story of “Scientific American”. “A limited number of components can be assembled in different ways and in different combinations to achieve the same winning structure.”
Cooper and other researchers see this evidence of convergent evolution as a sign of hope: the virus may have exhausted new ways to adapt to the current environment. He said: “Actually, this is just a small pile of cards right now.” “If we can control the infection, the pile of cards will be small.”
5. If the effectiveness of the vaccine begins to weaken, we can intensify the injection.
Eventually, the current vaccine will fail. “This is to be expected,” Chandland said. But he expects this to happen gradually: “The next generation of vaccines will have time.” Moderna has already begun testing the efficacy of booster injections used to prevent B.1.351 (first discovered in South Africa).Last week company Publish preliminary results. The current third dose of covid-19 injection or the specific booster dose of B.1.351 can enhance protection against the first discovered variants in South Africa and Brazil. But the new variant-specific booster elicited a greater immune response against B.1.351 than the third dose originally injected.
This is a relief for several reasons. First, it proves that variant-specific boosters can work. Cooper said: “I think the feasibility of these RNA-based vaccines to enhance vaccine production is our lifetime achievement.”
[ad_2]
Source link
