Antibodies are produced by our bodies when we are infected with a virus. In some diseases, these same antibodies can prevent us from being re-infected with the same virus. Following the coronavirus outbreak, researchers have been investigating how long these antibodies last in people who contracted COVID-19. So what does this all mean?
As yet, it is still unclear as to whether you can catch the coronavirus twice.
The CDC says it is “very uncommon” for a patient get COVID-19 more than once.
But experts are largely in agreement that those who have contracted covid will have some form of short term immunity because their body will have developed protective antibodies to help fight off the infection.
However, officials urge those who have had the virus to exercise caution.
Coronavirus tests are being rolled out for those who are suffering from the symptoms, such as a cough, fever or a loss of smell or taste.
Some people have been given antibody tests, which can detect whether a patent has previously suffered from the virus based on the number of antibodies in their blood.
Infectious disease expert Amesh Adalja warned “you should not really change your behaviour based on the results” of an antibody test as it’s unclear how long these antibodies stay in your body for.
Though these types of tests are not widely available for the public, they have been crucial in studying the new virus.
How long do covid antibodies last?
In a recent study, scientists analysed the immune response of more than 90 patients and healthcare workers at Guy’s and St Thomas’ NHS foundation trust.
And the findings could be exceptionally important for the long term plan protecting the UK against cover.
The research discovered that while 60 people of people studied had a “potent” antibody response at the peak of their infection with coronavirus, only 17 percent had the same potency when tested again three months later.
So it suggests that people who have recovered from COVID-19 may lose their immunity to the disease in just months, which could mean the virus may reinfect people year after year unless a vaccine is found.
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Dr Katie Doores, lead author on the study at King’s College London, said: “People are producing a reasonable antibody response to the virus, but it’s waning over a short period of time.
“Depending on how high your peak is, that determines how long the antibodies are staying around.”
The study found that antibody levels fell as much as 23-fold over the three month period period, and in some cases even became undetectable.
Another study published in The New England Journal of Medicine also suggests that antibodies developed after a mild infection and disappeared within a few months.
Analysing samples from 34 participants, they found the antibodies had a half-life of 73 days – meaning half of the antibodies would have disappeared after 73 days.
The study’s authors, led by Otto Yang, “call for caution regarding antibody-based ‘immunity passports,’ herd immunity, and perhaps vaccine durability.”
Dr Yang, of UCLA, added: “The big caveat is of course that this is just one snapshot for a relatively short period of time so we don’t know that it will continue that same rate of drop over time.”
The study also looked at those with milder symptoms, who typically produce less antibodies as their immune system response isn’t as strong.
Dr Yang said: “The majority just recovered at home with no hospital care, so their antibody titers [levels] weren’t extremely high.
“Indeed, we have seen other people that have very, very high antibody titers, on the order of 10 to 100 times higher than these.”
But the findings still have wide reaching implications for the development of a vaccine and the global plan in fighting the virus.
Buddy Creech, an infectious disease specialist at Vanderbilt University, concluded: “Infection with this coronavirus does not necessarily generate lifetime immunity.”