COVID-19 survivors’ immunity can last DECADES for some – but it only lasts for days for others and 11% never develop ANY protection against reinfection, study suggests
- Researchers looked at blood samples from 164 previously infected COVID-19 patients in Singapore
- About 11% never had detectable levels of neutralizing antibodies, while about 55% had declined within six months
- The remaining one-third had levels that did not fluctuate for at least six months and in some, the level rose even after that time frame
- Most patients had high levels of T cells, a type of white blood cell, even among the group that had never had detectable neutralizing antibodies
The duration of coronavirus immunity after infection can vary widely from person to person, a new study suggests.
Researchers found that some individuals who had neutralizing antibodies to COVID-19 antibodies saw the levels decrease after just a few days or even a few weeks.
But at least a third of the participants had no changes in levels after at least six months, and some even saw levels rise, suggesting their immunity could last for decades.
At least 10 percent never even had detectable levels.
The team, from Duke-NUS Medical School in Singapore, says the findings prove that some previously infected patients are more likely than others to be reinfected during subsequent waves, or even from highly contagious variants.
A new study from Duke-NUS Medical School in Singapore found that 11% of COVID-19 survivors never had detectable levels of neutralizing antibodies (far left), while about 55% decreased levels within six months (second of left and center)
The remaining one-third had levels that did not fluctuate for at least six months, and in some, the level rose even after that time frame. Pictured: A patient is tested to see if he has antibodies to the coronavirus in Baldwin Park, California, February 2021
“ The main message of this study is that the lifespan of functional neutralizing antibodies against SARS-CoV-2 can vary widely and it is important to monitor this at an individual level, ” said corresponding author Dr. Wang Linfa, director of the Program in Emerging. Infectious Diseases at Duke-NUS Medical School.
“This work may affect the lifespan of the immunity after vaccination, which will be part of our follow-up studies.”
For the study, published in The Lancet Microbe, the team looked at 164 COVID-19 patients in Singapore for six to nine months.
The patients each gave blood samples, which the researchers analyzed for neutralizing antibodies and for T cells, a type of white blood cell that binds to and kills viruses.
The data was then used to create an algorithm to predict the trajectories of neutralizing antibodies over time.
Participants were divided into five groups depending on how long their antibodies to COVID-19 lasted.
The first group, the ‘negative’ group, never had detectable neutralizing antibodies and constituted approximately 11.6 percent of the patients.
The next group, the ‘rapidly declining’ group, accounted for 26.6 percent of the patients and had different early levels of antibodies that declined rapidly, within a few days.
Subsequently, the ‘slowly declining’ group had antibodies that faded within six months, accounting for 29 percent of the participants.
The so-called ‘persistent’ group, comprising 31.7 percent of the participants, showed little change in their antibody levels for at least six months.
Finally, the delayed response group, 1.8 percent of patients, showed an increase in neutralizing antibodies during the study period.
However, the study found that most patients had high levels of T cells, even among those in the ‘negative’ group.
This means that individuals can still be protected if they have a strong T cell response, despite low levels of neutralizing antibodies.
‘Our study investigates neutralizing antibodies that are important in protecting against COVID-19. We found that antibodies against SARS-CoV-2 decrease at different rates in different people, ”said corresponding author Dr. David Lye, director of the National Center for Infectious Diseases in Singapore.
This highlights the importance of public health and social action in the ongoing response to pandemics.
“However, the presence of T cell immunity offers hope for longer term protection, which will require more studies and time to confirm epidemiological and clinical evidence.”