Why we need to get Covid booster jabs… but other vaccines last a lifetime: Data shows protection against infection fades within five months of the second dose 

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To overcome the pandemic, Britain has pinned its hopes on vaccines. But with signs that the protective effects of the two major jabs are wearing off sooner than expected, a booster program has just been launched, targeting 30 million Britons (including all over 50).

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The latest data shows that protection against COVID infection from the Pfizer-BioNtech and Oxford-AstraZeneca vaccines tends to fade within four to five months after the second dose.

The figures, which have not yet been published in a journal, come from the Zoi Covid study, which relies on an app used by more than a million people to collect data on infection rates.

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The latest data shows that protection against COVID infection from the Pfizer-BioNtech and Oxford-AstraZeneca vaccines tends to fade within four to five months after the second dose.

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The data shows that the AstraZeneca jab reduced the chance of infection by 77 percent when it was first given, but decreased to 67 percent after five months; Meanwhile, protection from the Pfizer vaccine fell from 88 to 74 percent.

At that rate of decline, the researchers warn, protection could drop to less than 50 percent by winter, especially among older people who have had earlier jabs and whose immunity may have been most eroded.

Similar findings came from a recent study from the University of Oxford, which looked at the efficacy of vaccines against the more virulent Delta strain.

Two weeks after it was given, the Pfizer jab reduced someone’s risk of developing a high viral load — the amount of virus circulating in their body — by 92 percent; This had dropped to 78 per cent 90 days after vaccination. In the same time frame, the effectiveness of the AstraZeneca jab dropped from 69 to 61 percent.

This is in contrast to other vaccines, such as measles, mumps and rubella (MMR), which last a lifetime. So why is it different from Covid vaccines?

Lawrence Young, a virologist and professor of molecular medicine, says, “To get long-lasting immunity, as you do with the measles jab, you usually need a live attenuated vaccine – which contains a very weak form of the virus. version.” Oncology at the University of Warwick.

These vaccines contain a mild form of the actual virus that is strong enough to trigger a strong, long-lasting immune system response. This is like effectively catching the virus, but without the symptoms.

The data shows that the AstraZeneca jab reduced the chance of infection by 77 percent when it was first given, but decreased to 67 percent after five months;  Meanwhile, protection from the Pfizer vaccine dropped from 88 to 74 percent.

The data shows that the AstraZeneca jab reduced the chance of infection by 77 percent when it was first given, but decreased to 67 percent after five months; Meanwhile, protection from the Pfizer vaccine dropped from 88 to 74 percent.

In contrast, the current crop of Covid jabs are mostly either a man-made version of a protein (spike protein) found in the virus, or genetic fragments of the virus.

Both prime the immune system to produce antibodies that patrol the bloodstream looking for symptoms of the virus.

Although they induce a less robust immune system response, synthetic copies of the spike protein and genetic fragments of COVID-19 – called mRNA – are much more stable and easier to control than vaccines made from live viruses, leading to large Scale production becomes easier.

However, at least one live COVID vaccine – called COVI-VAC – is in clinical trials, with results due in spring 2022.

The key to a vaccine’s long-term success is how the immune system responds to it.

It can be influenced by many factors, such as age, gender, ethnic background and underlying diseases, such as cancer, which can undermine the body’s defenses. When we become ill with an infection, the immune system’s B cells start producing antibodies to fight it. But once the immediate threat has passed, these antibodies are processed as waste.

To prevent recurrence, some B cells are converted into permanent, mini antibody factories, known as long-living plasma cells (LLPCs).

Anyone who has had COVID is likely to have these cells – and the sicker they were, the more likely they are to have LLPC, the greater the exposure to the virus, the stronger the immune response.

LLPCs do not always form following infection, but Dr. Steven Smith, a lecturer in biomedical sciences at Brunel University, says: ‘LLPCs can survive for many years in our bone marrow, continuously releasing antibodies.’

For example, people who caught SARS in 2003 still have antibodies circulating in their systems almost 20 years later. The hope was that COVID vaccines would have a similar effect, prompting the immune system to convert some B cells into antibody production lines.

But researchers in Belgium recently measured the levels of COVID antibodies in the blood at regular intervals in more than 200 people given the Pfizer vaccine, and found the levels halved within three months of the jab. This suggested that defenses were already weakening, according to findings published in July in Emerging Microbes and Infection.

Smith says that even if antibody levels decline, a vaccinated immune system is well equipped to deal with future threats. This is because B cells have an immunological ‘memory’ – meaning that if they are hit by the invasive virus again, they can start producing new antibodies almost immediately.

Professor Young says: ‘Your immune response will never be zero after getting vaccinated – it’s not like we’re back where we started before the jabs happened.’

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