A common belief is that once you get exposed to the COVID-19 virus, then a long-lasting immunity will develop, and there will be protection against COVID-19. That may not be the case.
Two preprint studies, from Wuhan, China, and Amsterdam answers those questions.
In both studies, the IgG or immunoglobulin G was tested. IgG confers “memory” to the immune system so that when the virus is reencountered, then the response time to fight the infection is much shorter and more effective. Thus preventing a full-blown disease.
Zhongnan Hospital, Wuhan University Study
The study from Wuhan with a combined sample size of 26,473 samples shows that the antibodies against COVID-19 will probably last for less than 6 months in the majority of those exposed.
They arrived at that conclusion after the test showed that only 4.6% of 3832 healthcare workers with an average age of 37 years developed antibodies in their blood. These health care workers were not tested to be positive for COVID-19 viruses. Still, they worked without proper personal protective equipment (N95 masks, gowns, head covers, goggles, and gloves during the early part of the pandemic from November 2019 to January 20, 2020. Thus they were assumed to have been infected.
They also tested general workers and other non-COVID-19 patients, and the results also showed low antibody concentration after several months.
In contrast, 89.8% of patients with recent COVID-19 diagnosis developed antibodies. This means that although IgG antibodies develop during COVID-19 exposure or illness, the protection it gives is only short-lived.
The study from Amsterdam showed that the antibodies developed against four different types of coronaviruses last for 6 months. After that, it slowly wanes off.
The four species of coronaviruses tested are HCoV-NL63, HCoV-229E, HCoV-OC43, and HCoV-HKU1.
This research started in 1985 until 2020. That’s why the SARS-CoV-2 virus that causes COVID-19 is not included in this study.
The test involved regular IgG blood tests against the four coronavirus species providing a total of 2,473 follow up months. The research showed:
Reinfections occurred frequently at 12 months post-infection and there was for each virus a substantial reduction in antibody levels as soon as 6 months post-infection.
MERS and SARS
MERS and SARS were previous epidemics of coronaviruses that attracted worldwide attention because of their higher mortality rates of 34.4% for MERS and more than 50% for those more than 65 years old for SARS.
Antibody studies showed that the immunity for both is that long-lasting either.
The antibodies against the Middle East Respiratory Syndrome or MERS lasted for only 34 months.
The SARS or Severe Acute Respiratory Syndrome coronavirus elicited immunity that only lasted for an average of two years.
If another epidemic of MERS or SARS happens again, the ones who had them before can be reinfected again.
What to Do Now?
People who are at high risks like diabetics and hypertensive should protect themselves by excellent control of their blood pressures and blood sugars.
A healthy diet and exercise can help a lot in decreasing their risks.
Proper handwashing and the use of hand sanitizers should be second nature by now for everybody. They are useful with or without pandemics.
Be sure to have adequate amounts of Vitamin C and Zinc to maintain a sound immune system.
There is good news, though. COVID-19, recent studies have shown that the COVID-19 may actually have low mortality. That’s the gist for the next article.
COVID-19 is a new disease and the information about it constantly evolves. The more we know about this new disease, the better we can handle it.
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Don’t Get Sick!
Reference:
- Wu, Li-Ping et al. “Duration of antibody responses after severe acute respiratory syndrome E.”merging infectious diseases, vol. 13,10 (2007): 1562-4. doi:10.3201/eid1310.070576
- Persistence of Antibodies Against Middle East Respiratory Syndrome Coronavirus. Medscape. Emerging Infectious Diseases. 2016;22(10):1824-1826.
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