When am I immune?

This post will answer these questions:

1. If I get sick and recover can I get sick again?
2. Am I immune from re-infection forever?
3. How do I know if I’m immune?

People often ask me how I feel. I usually tell them that for me, and I assume for other people with mild cases, this virus feels like having the flu. I have been blessed to never have had the flu (Vaccines rule!) but that’s what I’ve been telling people. In reality, the symptoms are unlike any illness I’ve ever had before. The cough is similar to a bad bronchitis, but the general feel of it is hard to describe. The best I can say is that its a full body ick. I just feel icky. This feeling is different from the muscle aches (those were unpleasant as well) . It’s more of a difficult to describe crummy feeling that is altogether miserable.

Fortunately for me, the acetaminophen helps and things are getting better with time, albeit slowly. Every day the ick fades ever so slightly. The problem is, that as the ick fades, the blah caused by being stuck in the basement increases. Now I have a dynamic combination of ick and blah, precisely tuned to create an overall sense of bleck. As you can see, it’s hard to describe.

Now that I am at day 6, and see that I am improving, even if slowly, I am confident I will not be one of the patients that deteriorates around this time. This creates optimism for full recovery.

I think it’s interesting to think about what ‘recovery’ means. I wrote a post about 2 months ago called “How this coronavirus makes you sick“. It was actually 2 days ago but it feels like 2 months when you are stuck in your basement (Is today Wednesday or Thursday?). I ventured to explain how this virus causes the particular symptoms it does. In that post, I described how many of the symptoms we feel are not caused by the virus itself but by the immune response to the virus. In other words, I am my own ick factory.

The immune system, like all things in biology, is a precisely tuned balance between components that crank it up and components that crank it down. These things are precisely in balance so that you can be prepared for an invader while not having the system running haywire at all times. When the coronavirus hits you, the balance shifts and the immune response escalates. Then, as the virus starts to be cleared, the system has to be turned down to prevent excessive collateral damage. In fact, it’s likely that elderly and chronically ill people are getting such a severe form of this infection because their immune system is unable to maintain this balance causing the system to go haywire. Turning it down, is just as important as turning it up.

With viral infections, your immune system first produces an antibody called immunoglobulin M or IgM. It’s the first responder antibody and offers a more general response to infection. As the infection progresses, the immune system starts producing an antibody called immunoglobulin G or IgG. This is a specific antibody that is more effective at neutralizing the intruder guilty of the current infection.

With recovery, the immune response is turned down but the IgG antibodies hang around. Eventually they decrease in numbers but don’t go away altogether. The body creates antibodies producing memory cells cells that circulate looking for the intruder to come back. If it does, they can ratchet up the immune response quickly so the virus is cleared before it makes you sick. This is how vaccines work. You get an injection of part of the virus and develop a mild immune response. You then get the memory B cells without getting the full disease.

The real question is whether this coronavirus will lead to life long immunity. Unfortunately, like most things in medicine, it’s not a yes or no answer. For some viruses, like measles and polio, these antibodies are around for your entire life, but for others it’s not so long. For some infections like tetanus you need a regular “booster” to prolong the immune response. Some viruses, like the flu, mutate and you need a new vaccine every year. The bottom line is, that not all viruses are the same in this regard.

Coronaviruses come in different flavors. There are the mild ones that cause the common cold. Immunity to these coronaviruses last only about 1-3 years. The severe coronavirus that is afflicting us now is more like the one that caused SARS outbreak in 2003. That one was named SARS-CoV1 and this one SARS-CoV2 because they are similar in many ways. Most people infected during with SARS-CoV1 outbreak developed immunity lasting 8-10 years. Another similar virus that caused the MERS outbreak a few years after SARS produced immunity that was not as durable.

This all leads to the following questions:

1. How long does immunity to this coronavirus last? The range of outcomes is one year to life long. Obviously that question can only be answered by testing people over several years to find out. If immunity is only for a short time, this raises the concern of a resurgence of the pandemic. I don’t want to go through this again and I’m sure you don’t either.
2. If people have a mild case or have no symptoms at all does that mean their immunity will not last as long or does it mean that they did such a good job making antibodies that it will last longer?

These are very important questions for a number of reasons:

1. If people are immune they can return to the workforce and regular life without fear of spreading the disease or getting sick again themselves. This would help the economic fallout.
2. We could reintroduce immune doctors and nurses to fill in the vacancies caused by sick hospital staff. Perhaps all the recovered doctors and nurses could help out in New York. You can also see how flattening the curve would be important here since it would allow healthcare workers who got sick time to recover and return to work before there are too many patients in the hospital.
3. If immunity is durable it means that vaccines will be more effective. And if I hear ONE WORD from an anti-Vaxxer I will cough all over them!

The main problem I am seeing currently is that there are many people who are sick and are not getting tested. They are appropriately assuming they have the coronavirus, but may have something else. I had a patient in the ICU last week who had all the symptoms but it turned out he had the flu (COVID-19 testing was negative). One of the nurses who I exposed felt sick and stayed home. She eventually got tested and was negative (talk about a bad time to get a cold). What this means is that there are people who will assume they are immune to COVID-19 when in fact they never had the disease to begin with. It’s not like the rest of the viruses are taking a vacation. Millions of people may get a virus at this time which has nothing to do with COVID-19. They will then think they are immune when they are not and stop all the usual precautions. This will increase the risk of a resurgence of the pandemic. Another issue would be if people get a mild infection which does not create a robust enough response to generate protective antibodies. There are currently companies and health departments working on developing testing to see if there are IgG antibodies which would be proof of immunity and should solve this problem but remember how hard it has been to get the initial testing scaled up.

Since I have a confirmed case, I am confident I will be immune after recovery. I just don’t know for how long. If immune I will be able to do all the dangerous stuff in the hospital such as the aerosolizing procedures and fill in for people when they get sick. In a way this feels like a bit of a superpower but is nothing special and hopefully its a power we all will share soon so we can put this virus in the history books.