Dear Reader:

In my April 12 post, I quoted from Healthline regarding herd immunity: “Herd immunity happens when so many people in a community become immune to an infectious disease that it stops the disease from spreading. It can happen in two ways: 1. Many people contract the disease and in time build up an immune response to it (natural immunity) 2. Many people are vaccinated against the disease”- because vaccination is not possible this year, let’s look at natural immunity, that is, people who were infected, producing antibodies that protect them from getting infected a second time:

www. msn. com/ en-ca/ health/ medical/ can-you-catch-coronavirus-twice-south-korea-reports-91-recovered-patients-tested-positive,  April 11, reads: “The Korea Centers for Disease Control and Prevention announced that 91 people who had previously cleared of the virus had tested positive… KCDC director Jeong Eun-kyeong said Friday that health investigators were still working to determine whether the patients had been ‘reactivated’ rather than being re-infected. ‘While we are putting more weight on reactivation as the possible cause, we are conducting a comprehensive study on this.’ Jeong said… The question about reinfection also arose last month after health officials in Japan said a woman who had been declared virus-free had tested positive again…Although uncommon, some viruses stay dormant inside host cells until they’re reactivated. Chickenpox, for example, can occur in children but can later reactivate in adults as shingles.”

“David Kelvin, a professor of microbiology and immunology at Dalhousie University, said reinfection is ‘unlikely’ and there could be several possible explanations for the new cases, including that the individual never completely cleared the original infection or the use of faulty test kits… If it’s true that people are re-infected, we’re in for a really difficult time. I find it hard to believe, but it’s possible”.

“Kelvin said there have been few studies done on reinfection, but they have so far found it’s unlikely that people can get the novel coronavirus more than once. He pointed to one small study from China that found antibodies in rhesus monkeys kept primates that had recovered from Covid-19 from becoming infected again upon exposure to the virus”.

“Whether or not people who have Covid-19 can be re-infected is currently being studied closely by health experts… Anthony Fauci, the director of the U.S. National Institute of Allergy and Infectious Diseases, told the Journal of the American Medical Association this week that reinfection was unlikely. ‘If a person gets infected with coronavirus A, and then gets reinfected with a coronavirus, it may be coronavirus B’, Fauci said. ‘But right now, we don’t think that this is mutating to the point of being very different.”

www. iflscience. com/ health-and-medicine, on April 14,  on the same topic, reads that Jeong Eun-kyeong, director of the Korean Center of Disease Control and Prevention (KCDC), told reporters on April 13: “Investigators are looking into whether the cause of the relapse is the virus being reactivated or reinfection with the virus”. The article continues: “The big questions are whether or not people are at risk of falling ill again and whether they transmit the infection to others. In short, no one knows yet. As with many aspects of this novel disease, the scientific community has little in the way of pre-existing knowledge on Covid-19 and the planet’s understanding is constantly evolving”.

“The US Centers for Disease Control and Prevention (CDC) .. ‘Patients with MERS-Cov (a related coronavirus) are unlikely to be re-infected shortly after they recover, but it is not yet known whether similar immune protection will be observed for patients with Covid-19′”.

Professor Jimmy Whitworth, an expert in international public health from London School of Hygiene and Tropical medicine  said: “I suspect it’s a technical issue, rather than a repeat infection.. It looks like you are immune for getting it again, but for how long, we don’t know yet”.

My summary:

1. SARS-Cov-2, the virus causing Covid-19,  is a new virus which appeared in humans for the very first time in Nov 2019, and got the massive attention of the international scientific community sometime this year, not before. Scientists don’t yet know this virus well.

2. It is possible that the positive results in patients that recovered from Covid-19 are false positives, or that their previous negative results were false negatives, and/ or other technical malfunction, and therefore, these reported positives do not mean that recovered patients were re-infected.

3. It is possible that this new virus, after infecting a patient, goes dormant, similar to a herpes virus that goes dormant following the initial, first activations, then gets re-activated every so often, staying in the person’s body lifetime.

4. It is possible that this new virus will significantly mutate to a new form or forms, so that a person’s antibodies following the first infection are not effective when a second infection takes place. In this case, a person’s natural immunity for the original virus will be limited in time. But so far, this virus didn’t mutate significantly (all viruses mutate to some extent when infecting new individuals). If this new virus does mutate significanlty, it can re-infect recovered Covid-19 patients in the same way that mutated/new flu viruses re-infect recovered flu patients.

anita