The novel coronavirus started spreading in December 2019, and since then, it has rippled across the globe, affecting 187 countries and territories, and infecting more than 3.18 million people. However, the behavior and mechanism of the virus, including whether it provides adaptive immunity, is still unclear. There have been reports of reinfection out of South Korea and Japan.
Now, a team of scientists at Columbia University Mailman School of Public Health aimed to shed light on the issue of protective immunity to SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) and if recovered patients can become re-infected. The research is published on the preprint server medRxiv*.
The team found that reinfections with endemic human coronaviruses are not uncommon, even within a year of prior infection. They studied four common human coronaviruses, excluding the SARS-CoV-2.
Human coronaviruses, HKU1, 229E, OC43, and NL63, cause a wide range of respiratory diseases, including pneumonia. However, these coronaviruses may only cause mild to moderate disease and occur now and then, unlike SARS-CoV-2, first reported in China.
“As the COVID-19 pandemic progresses, infecting millions of people worldwide, a key question is whether individuals are prone to repeat infection. The evidence from endemic coronaviruses suggests that immunity is short-lived, and reinfection is common within one year, with symptom severity possibly more a function of genetics than the presence or absence of antibodies. Research on endemic coronaviruses, along with findings for SARS and MERS, provide context for understanding protective immunity against repeat SARS-CoV-2 infections,” Dr. Jeffrey Shaman, professor of environmental health sciences, said.
Understanding for repeat infection risk
Respiratory viral infections in humans, which may range from common colds to severe respiratory disease, signify a huge global health burden in developing countries. Human coronaviruses (HCoV) are tied to a wide range of upper respiratory tract infections, and on some occasions, lower respiratory tract infection. Though they come seasonally, only a few long-term studies analyzed the prevalence of HCoV strains and their clinical manifestations.
The current global pandemic has negatively impacted not only developing countries, but even first world countries, such as the United States, the United Kingdom, and other European countries. It is essential to determine reinfection in SARS-CoV-2 to prevent the further spread of the virus. The scientists believe that by studying reinfection rates in other human coronaviruses, they may provide insight if the phenomenon happens in COVID-19.
There may be two processes that can be responsible for short-lived immunity to endemic coronaviruses. First, the waning of antibodies and memory cells over time may affect a person’s immunity to a human coronavirus, and there can be an antigenic drift or mutation of the virus or pathogen that enables them to evade the immunity established against the previous strains.
Children more likely for reinfection
To arrive at their findings, the researchers utilized data from proactive sampling in New York City between the fall of 2016 and the spring of 2018. They combined weekly nasal swab collection and self-reports of respiratory symptoms from 191 participants. The team used the data to investigate the profile of recurring infections with endemic coronaviruses.
Of the 191 participants, 86 tested positive at least once during the study for 144 any coronavirus infection. About 48 patients tested once for OC43, 31 tested posted positive for 229E, 15 tested positive for NL63, and 28 tested positive for HKU1.
Among the human coronaviruses, OC43 is the most diffused, which is the likelihood of testing positive following 80 weeks in the study was 0.47. Further, the least frequently isolated coronavirus was NL63. The average time between reinfection was roughly 37 weeks, and among the 12 individuals who tested positive twice, nine were children between one and 9 years old, while three were adults between 25 and 34 years old.
“This study provides evidence that reinfections with the same endemic coronavirus are not atypical in a time window shorter than one year and that the genetic basis of an innate immune response may be a greater determinant of infection severity than immune memory acquired after a previous infection,” the researchers concluded in the study.
The team revealed that when reinfection happens, it is not tied to less severe symptoms. Instead, certain genetic factors may contribute to the severity of an infection. This means that those who were asymptomatic during the first infection did not experience symptoms even during subsequent infections. Also, the members of the same family reported similar symptom severity.
medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.