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The effectiveness of the COVID vaccine has diminished over time, but it still prevents death and serious illness.

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Some countries-include England— We are currently offering a third COVID-19 shot, as the vaccine’s effectiveness has been reported to decline over time. But do these countries really need to embark on a broader booster campaign? This is what previous studies have shown how vaccines work.

In one study, four months after the second dose, Pfizer / BioNTech vaccination Not very effective in preventing infection (classified as positive PCR test) 96% to 84%.. However, this study is a preprint, which means that the results have not yet been formally reviewed by other scientists.

Similarly, the actual data from Israel It has been suggested that people over the age of 60 who received a second dose of Pfizer vaccine in March 2021 were 1.6 times more protected from infection than those who received a second dose two months ago. increase. However, looking at other age groups, the data was not very clear. This study has not yet been peer reviewed.

Data from the Moderna vaccine show that functional antibodies (those that can prevent the virus from entering cells) persisted for 6 years in most people. A few months after vaccination.. However, the performance of the virus against beta variants gradually declined, and this study did not evaluate vaccines against the currently predominant delta variants.

NS Another preprint Examining the effectiveness of the vaccine against the Delta, we found that both the Oxford / AstraZeneca and Pfizer vaccines were less effective in preventing infection in the face of this variant.Similar findings Reported According to the US Centers for Disease Control and Prevention.

All of these studies may sound alarming, but most have not yet been formally reviewed, so the results should be treated with caution. It also measures a variety of things. Some people look at the number of positive PCR tests, not the symptoms or illness.Others think Antibody level Or response to various variants. Indeed, when assessing performance, you need to consider what the most important goals of vaccination are.

Vaccine is still protective

The ideal vaccine completely prevents the infection and prevents people from catching and spreading the virus. However, in the early stages of the pandemic, it has been reported that people re-infected with COVID-19 and antibodies have declined, and high levels of antibodies are thought to be important in preventing the onset of infection. As a result, it has long been suspected that it is impossible to create a vaccine that completely blocks the infection.

Indeed, antibodies are just one indicator of an effective immune response. We also need T lymphocytes that kill the virus and immunological memory that allows us to quickly and mass-produce these killer T cells and antibody-producing B cells. The news here is much more positive. Studies have shown that both killer T cells and immunological memory persist well.

What this means is that some people may not have enough antibodies to completely prevent the infection, but they can still repel the infection and stop it from colonizing. In this case, the vaccine is expected to reduce the effects and severity of the disease. And this is where we are seeing the good news.

Report England And that We The number of vaccinated people who need hospitalization or development is decreasing Severe symptoms From the delta variant. For example, fully vaccinated people in the United States It is shown You are one-fifth more likely to get infected with COVID-19 and one-tenth more likely to be hospitalized or die.

Similarly Israeli study As mentioned above, in people aged 40-59 years 4 months after vaccination, the vaccine was shown to be 98% effective in preventing hospitalization with COVID-19. After 6 months, protection remained high at 94%.

However, for people over the age of 60, the data show a significant decline in performance, with protection against hospitalization reduced after 4 months (91%) and 6 months (86%). This difference may be due to the inability of older people to initiate a good immune response after vaccination and the challenge of delta mutants.

But what is clear is that the vaccine is very effective in protecting against serious illness compared to unvaccinated people. And this is really the most important goal of vaccination — to prevent people from getting sick and dying.

Turn on the booster

Despite protection against serious illnesses that remain high for months after vaccination, many governments have chosen to launch a vaccine booster program. Is the third dose deployed by the UK and other governments sufficient to provide the most vulnerable people with long-term, higher levels of protective immunity? The truth we don’t know yet.

It should be remembered that vaccination is just one way we can protect ourselves infection, And even if sufficient protection cannot be achieved, other measures such as wearing a mask and ventilation may be required.Certainly, not only boosters, but also the British government Outline of the plan To reintroduce telecommuting and wearing masks during the winter, in case the virus can get out of hand.

Another question we have to ask ourselves is whether we should actually look to help other vulnerable people around the world.To the wealthiest country Enough vaccine Even if boosters are already in use and your child is vaccinated.

The most important goal of vaccination is to protect yourself from severe illness and death, but in many countries Not even giving 2% of their population With the first vaccination, the virus can propagate at a huge cost. Can we really take a different perspective?


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The effectiveness of the COVID vaccine has diminished over time, but it still prevents death and serious illness.

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