(CNN) — Now that most cities and states in the US have lifted requirements to wear masks and other precautions against Covid-19, you may be wondering what your chances are of getting infected or, worse, being hospitalized. or die if you get sick.
Researchers have studied this question and, overall, have found that for people who are up-to-date on their COVID-19 vaccinations (that is, get a booster when recommended), protection against disease subsides three to four months after the last dose, but protection against hospitalization and death remains high.
Here’s why: Antibodies – the immune system’s first line of defense – gradually decline after an infection or vaccination. Over a few months, they disappear, and that’s normal. But this leaves the body open to another viral invasion.
The good news is that although the immune defense begins with antibodies, it does not end there. Other cells, such as B lymphocytes and T lymphocytes, retain the memory of the virus or the vaccine, so they can make another army of antibodies if they encounter that pathogen again.
It takes some time to build that army, so as your body prepares to fight, you may experience some symptoms. Ultimately though, your immune system should come to the rescue and help you bounce back without too much trouble.
In general, this is how it is supposed to work. But sometimes this process doesn’t go as planned for everyone. Older adults and people with lower immune function may need extra help to avoid the worst consequences of a COVID-19 infection.
Protection after covid-19 infection
Los submitted data This week the Advisory Committee on Immunization Practices of the US Centers for Disease Control and Prevention breaks this down.
This is how protection is maintained in real life against an infection with the symptom-causing variant of the omicron coronavirus. If you have:
- Two doses of the Johnson & Johnson vaccine are 30% effective two to four months after their vaccinations.
- One dose of Johnson & Johnson and one dose of a Pfizer/BioNTech or Moderna mRNA vaccine are 55% effective between months 2 and 4.
- With three doses of an mRNA vaccine, their vaccines are 63% effective between months 2 and 4.
After five months, booster doses offer almost no protection against omicron infection, according to data from the UK Health Security Agency.
Protection against hospitalization with a weak immune system
When it comes to urgent care or hospitalization, the protection you get from vaccines depends on your immune system.
Sara Tartof, an epidemiologist at Kaiser Permanente in Southern California, has been studying the effectiveness of a third dose of Pfizer’s mRNA vaccine in keeping adults in her health system out of the hospital.
Up to three months after the third dose, the vaccine’s efficacy against hospitalization was 85%, but fell to 55% after three months. However, upon further analysis, he found that these results were largely due to the immune system.
“We didn’t see any evidence of decline except in the immunocompromised,” Tartof said. “In the immunocompromised, the efficacy of the vaccine basically starts out low and goes down.”
But for people with normal immune systems, the vaccine’s efficacy against hospitalization was still high, around 86%, after three months.
The results of their initial study were published in The Lancet Repiratory Medicine. Tartof says that he plans to update them soon with the immune system results.
Overall, researchers are finding that for adults age 50 and older with normally functioning immune systems, protection starts out high and stays high — about 84% — for up to six months after a dose booster, when there is a risk of being hospitalized for an infection caused by the omicron variant.
For adults age 50 and older who have reduced immune function, such as those who have undergone solid organ transplants or are undergoing cancer treatment, protection from a booster is initially good but declines more rapidly .
For example, up to two months after a booster dose of an mRNA vaccine, an immunosuppressed adult can expect 81% protection against hospitalization for an omicron variant infection, but that protection is reduced to about 49% after four months, according to new data from the CDC. This is one of the reasons why this group has been prioritized for additional reinforcements.
Immune protection after infection
A study 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 unvaccinated and uninfected people. People who had recovered from the infection were 88% less likely to be hospitalized than those who were not vaccinated.
The researchers stated that this protection was on par with that conferred by mRNA vaccines and was stable up to nine months after infection.
The CDC states that approximately 90% of people who become infected with COVID-19 develop antibodies after infection. But the degree of protection you get from an infection depends on the symptoms. People with symptoms will make more antibodies than those without, and people who were hospitalized make more antibodies than those who weren’t.
However, all bets are off when it comes to omicron. A recent study in Qatar found that while a previous infection was highly protective – around 90% – against re-infection with alpha, beta and delta variants, it was only 56% protective 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 deadly. But if you’ve had one, you probably have some protection against it, and people should be able to count on that when thinking about risk, said Dr. Dorry Segev, a transplant surgeon at the College of Medicine Grossman of NYU, to Dr. Sanjay Gupta, chief medical correspondent for CNN.
“Covid is a high-risk, high-consequence way to get immunity. But, if you’ve had covid and you’ve been through it and you have immunity, that’s something that we have to respect and we have to incorporate into the ways that we draw the covid new social contract,” Segev said.
