Studies show covid vaccine protects twice as long as natural immunity
Share this post:
New medical studies are examining both the length of natural immunity in patients who have recovered from covid-19, as well as the effectiveness of the Moderna vaccine in producing antibodies to combat the virus.
A study published in BioMed Central found that fewer than half of 37 covid-positive patients retained their disease-fighting antibodies more than 100 days after infection.
Natural immunity occurs through exposure to the actual disease organism, and not from a vaccine. It can be long-lasting but varies widely, with a half-life from about 11 years for tetanus to over 200 years for measles and mumps. Covid-19, researchers said, behaves more like the seasonal flu, with natural immunity lasting less than a year.
Scientists from IGeneX Laboratory in Milpitas, Calif., looked at samples from 37 patients, obtained at different times after they’d received a positive covid test result.
“Our lab received a few hundred covid and non-covid blood samples from another lab (Medical Art Center in New Jersey),” said IGeneX public relations head Joe Sullivan. “We then tested these samples using our proprietary ImmunoBlot technology to get the sensitivity/specificity figures. For the covid-positive group, we tested the samples over a long period to see how long antibodies remained present.”
According to the study, only 44% of patients retained antibodies beyond the 100th day.
“The fact that 56% of subjects lose virus-neutralizing antibodies after only a few months could explain the timing of successive waves of the disease,” said Dr. Jyotsna Shah, lead author for the study. “We saw a big surge in cases in the fall of last year, and additional hot spots have popped up in 2021.”
A second study, published in the New England Journal of Medicine on April 6, looked at 33 patients between 18 and 55 years old, with early results indicating the Moderna vaccine was 94% effective in preventing covid-19.
The study also found that antibodies produced in patients who received the Moderna vaccine persisted for at least six months following the second vaccination dose.
That is twice as long as the natural immunity observed in the IGeneX study.
Shah said additional studies are ongoingto monitor long-term immune response for both natural and vaccine immunity, and said the results underline the importance of continuing simple health and safety measures such as mask wearing.
“Whether you’ve recovered from covid-19, received the vaccine, or neither, understanding immunity and how long it lasts can help give you important insight into how you can interact safely with others during the pandemic,” Shah said. “Because we are still learning about the length of immunity, practicing social distancing and wearing a mask need to continue to stop the spread.”
More than 8.4 million people in Pennsylvania (49% of residents) have at least one dose of a coronavirus vaccine, and more than 3.4 million have been fully vaccinated (30.3% of residents), according to the data released by the state on Friday.