How well does our immunity to Covid-19 last?
How well does our immunity to Covid-19 last?

How well does our immunity to Covid-19 last?

Researchers have dug into that question, and in general, they have found that for people who are considered to be up to date with their Covid-19 vaccines – that means they get a booster when recommended – that protection against disease drops over three or four months after your last dose, but protection against hospitalization and death remains high.

Here’s why: Antibodies – the front line’s immune system defenders – gradually drop after an infection or vaccination. Within a few months, they disappear and that is normal. But it leaves your body open to yet another viral invasion.

The good news is that even though the immune system starts with antibodies, it does not end there. Other cells such as B cells and T cells remain imprinted with the memory of the virus or vaccine so that they can make another antibody army if they encounter that pathogen again.

It takes some time to build that army, so while your body is preparing to fight, you may get a few symptoms. Ultimately, though, your immune system should come to the rescue and help you recover from too much fuss.

In general, this is how it should work. But sometimes this process does not go as planned for everyone. Older adults and those with lower immune function may need extra help to prevent the worst outcomes of a Covid-19 infection.

Protection after infection

Data presented this week to the U.S. Centers for Disease Control and Prevention’s advisory committee on vaccination practices breaks this down.

Here’s how the protection lasts in real life against an infection with the Omicron coronavirus variant that causes symptoms. If you got:

  • Two doses of the Johnson & Johnson vaccine, they are 30% effective between two and four months after your shots.
  • One dose of Johnson & Johnson and one dose of mFR shot from Pfizer / BioNTech or Moderna, your vaccines are 55% effective between the 2nd and 4th month.
  • Three doses of one mRNA shot, your vaccines are 63% effective between months 2 and 4.
After five months, boosters offer almost no protection against Omicron infection, according to data from the UK Health Security Agency.

Protection against hospitalization with low immune system

When it comes to emergency care or hospitalization, the protection you get from vaccines really depends on your immune function.

Sara Tartof, an epidemiologist for Kaiser Permanente in Southern California, has investigated how well a third dose of the Pfizer mRNA vaccine manages to keep adults in her health system out of the hospital.

Up to three months after a third dose, the efficacy of the vaccine against hospitalization was 85%, but it decreased to 55% after three months. On closer inspection, however, she found that these results were largely driven by immune status.

“We saw no signs of diminishing, but in the immunocompromised,” Tartof said. “In immunocompromised people, vaccine efficacy basically starts low and gets lower.”

However, for people with regular immune function, vaccination efficacy against hospitalization remained high – around 86% – after three months.

Her first survey results have been published in The Lancet Repair Medicine. Tartof says she plans to update them soon with results by immune status.

In general, researchers find that for adults 50 and older whose immune system is functioning normally, protection starts high and stays high – around 84% – for up to six months after a booster dose when it comes to the risk of being hospitalized with an infection. caused by the Omicron variant.

For adults aged 50 and over who have impaired immune function, such as those who have had solid organ transplants or who are receiving cancer treatment, protection against a booster is initially good, but it drops faster.

For example, an immunocompromised adult can expect 81% protection against hospitalization up to two months after a booster dose of an mRNA vaccine if they get an infection caused by the Omicron variant, but it drops to about 49% after four months, according to new CDC data. This is one of the reasons why this group has been prioritized for additional boosters.

Immune protection after infection

ONE examination published this week in the journal JAMA Network Open found that unvaccinated people who had recovered from Covid-19 were about 85% less likely to get it again, compared to people who were unvaccinated and uninfected. People who had recovered from the infection were about 88% less likely to be hospitalized than those who were unvaccinated.

The researchers said this protection was on a par with that given by mRNA vaccines and remained stable up to nine months after infection.

The CDC says that about 90% of people who receive Covid-19 will generate antibodies after their infections. But how much protection you get against an infection depends on your symptoms. People with symptoms will produce more antibodies than those without, and people who were hospitalized make more antibodies than those who were not.

However, all bets are off when it comes to Omicron. One recently examination from Qatar found that while a previous infection was extremely protective – around 90% – against re-infection with the Alpha, Beta and Delta variants, it dropped to only 56% against Omicron. Serious outcomes after infection were rare.

Experts agree that getting a Covid-19 infection is not a good way to build immunity because it can be so unpredictable, even fatal. But if you have had one, you probably have some protection against it, and people should be able to count on that when they think of risk, said Dr. Dorry Segev, a transplant surgeon at NYU’s Grossman School of Medicine, to CNN Chief Medical Correspondent Dr. Sanjay Gupta.

“Covid is a high-risk and high-impact way to get immunity. But if you had Covid and you went through it and you have immunity, it’s something we have to respect and we have to incorporate it in those ways. , we sign new social contract of Covid, “said Segev.

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