Re-infection of Covid-19 — everything you need to know about this.
Many of you may have read about the first documented case of re-infection. I thought I could expand on this today to help you understand this a bit better.
1- As I mentioned earlier in my Vaccine post, until now, there were no accurate reports of re-infection. What we have found is leftover viral debris that is picked up by a PCR, as it is not able to differentiate between infectious vs non-infectious viral matter. This is the first documented case of re-infection.
2- What we know so far: this individual was first diagnosed with COVID-19 end of March. During his first Covid-19 infection he had mild symptoms including a cough, sore throat, headache and fever for several days. Four months later, he was returning to Hong Kong from Spain and tested positive for the SARS-CoV-2 virus at the Hong Kong airport screening last week.
3- On his second infection, he didn’t have any symptoms.
4- Re-infection was confirmed due to elevated CRP (a biomarker of inflammation/infection), high viral load with gradual decline and seroconversion of IgG antibodies.
5- Genome analysis showed a completely different virus strain from the first infection.
6- While immunity was not enough to block reinfection entirely, it absolutely protected the person from the actual disease. Remember, you can have the virus but not have the disease.
7- Antibody tests showed that the patient did not have any detectable antibodies to SARS-CoV-2 when he was re-infected but as they continued to monitor him, he developed detectable antibodies after reinfection. This is very important because it tells us that immunity continues even though there are no detectable antibodies after an infection, or if the antibodies wane after an infection — as we have seen with other antibody studies. Also remember that antibodies are only one part of the innate immune response, majority of the antibody studies do not test for memory B or T cells as these assays are much more difficult to conduct than antibody tests.
8- What we don’t yet know is whether he would still be infectious during his second infection. While we need data to understand this, given the virus was instantly neutralized, it does leave the likelihood of transmission on re-infection possible.
9- Importantly, it also tells us that while the virus has mutated, the mutations are not significant, and the body is able to recognize and generate a targeted immune response. We saw this in studies using convalescent plasma as well. This is especially important for the vaccines in development.
10- Lastly, this needs to end the herd immunity without vaccination discussion once and for all. We have known for a while that herd immunity is unattainable due to the sheer collateral damage. Now we know that herd immunity cannot possibly eliminate SARS-CoV-2 due to the potential of re-infection.