The 12+ million people in the US, and 60 million worldwide, who have been infected with COVID-19 — and survived — are likely asking themselves the same questions: am I immune now? Is it over or do I have to brace myself for the possibility of a reinfection? Moreover, could the second time potentially be worse than the first?
I was diagnosed with COVID in March of this year. After spending ten days in the hospital, and one night in the ICU, it took another 2 months for the air-hunger, headaches and fatigue to completely resolve. Compared to many other unfortunate victims, I did alright — and I am very grateful for the care I received. Now, as the surge in cases takes new life, I will be on the frontlines taking care of patients. Having had an eventful personal encounter with the virus, I now have a unique vantage point and remain fully committed to paying my fortunate circumstances forward. Although I can’t help but wonder about the same question faced by millions of others: am I safe now?
It is no surprise that studies have shown healthcare workers comprising 6% of COVID hospital admissions, with one-third of these admissions being nurses. Recently, we heard that over 900 healthcare workers at Mayo Clinic had acquired the infection in the first 2 weeks of the ongoing second COVID surge. Are these frontline workers protected? Can they return to work with no fear of a re-run? Or for that matter anyone who has been afflicted by COVID, are they now forever immune?
There are no clear answers here. But to understand this a little, let’s quickly revisit some basic principles of immunity.
Simply put, there are two forms of immunity: innate and adaptive. Innate immunity encompasses our body’s natural protective mechanisms that come into play almost immediately. This enables recognition of the virus and activates an immediate antiviral defense and attempt at removal of the infective agent. This, however, does not always do the job. Accordingly, a couple weeks after the initial exposure to the pathogen, adaptive immunity is invoked. Circulating white blood cells within our body recognize the virus and set off an immune response, involving the activation of T and B cells that actively attack the infective agent. It is this T and B cell-mediated immunity that should protect one against a second infection with the same agent.
What about Herd immunity?
Herd immunity is a form of immunity that is defined by essentially yielding to the virus, and letting it spread naturally in order to develop community-wide immunity. By consequence of a large proportion of the population becoming immune after exposure to the disease, person-to-person spread can potentially be mitigated. However, this does not confer immunity to the virus at the individual level, but rather reduces the risk of vulnerable people coming in contact with the pathogen. Unfortunately, depending on herd immunity as a way to deal with COVID-19, has not worked well — even in well contained countries like Sweden, where a disproportionate number of their most vulnerable populations have died. It is self-evident that containment strategies with vaccination may be our best way forward to achieve herd immunity. Not surrendering to the virus.
Am I safe from reinfection?
In all honesty, we’re not entirely sure. But it is important to recognize a few points when considering your relative safety:
i) The immune system is far from perfect. Not everyone has a robust immune response. And in those that do, the immune response can wane over time, potentially allowing for reinfection. There have already been some clearly documented reinfections: four that have been confirmed and published; two patients (in Nevada and Ecuador) actually fared worse the second time around.
ii) The virus can mutate and escape detection by the immune system. One could still be susceptible to reinfection from a different strain. At least this remains the case with the influenza virus. There is some evidence that SARS COV2 does not mutate rapidly, and hence this may not be a problem. But we don’t know for certain, at least as of yet.
iii) Even a vigorous immune response can be overwhelmed by the virus. It is unclear if the relative length of time and the amount of virus exposure could undermine a previously primed immune system.
Is it safe for me to be around others?
A prior infection and a consequent healthy immunity may help you combat a reinfection but does not prevent you from harboring or carrying the virus. You may be asymptomatic, but you can still be a carrier and spread the infection. I am a strong advocate for limiting your exposure to others no matter your previous exposure-status in order to limit the spread of the virus.
So, what should I do?
I guess the answer is that you can’t be too careful. Not everyone has had their antibody levels tested and even if positive, it is unclear how well that affords protection. It is best to presume that you are vulnerable for a reinfection and that you can still carry and spread the virus. This may be the safest approach till we actually achieve herd immunity through vaccination. Even then, for a period of time, there will remain a sense of uncertainty. So, containment strategies inclusive of distancing and masking will and should remain a way of life at least till mid-2021, when we will be in a better position to reassess the landscape.
The surge is back. As I repay my debt and get back to the frontline, I will continue to MASK up, and practice distancing. I have had a decent immune response to the virus, but I am taking no chances on getting reinfected or being an asymptomatic carrier and I implore you all to do the same.