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Of the many questions regarding COVID-19, one big one is whether people who become infected with SARS-CoV2 (the virus that causes COVID-19) will be able to be vulnerable to a second infection with the same virus. This is a big, complicated question, because there are some viruses that confer long-term immunity in those who become infected and sick, while other viruses stimulate the immune system to mount defenses that do not last for many years. Known as sterilizing immunity, this is the phenomenon in which the immune system learns to recognize the disease-causing agent, eliminate it from the body, and, if the person is ever exposed to the agent again, be able to eliminate it so quickly and completely that it will not make the person sick, while also neutralizing it so that the person cannot spread it to somebody else. Sterilizing immunity is what a person develops from certain diseases for which the earliest vaccines were developed, such as smallpox, measles, rubella, and mumps. Developing such illnesses once confers long-lasting immunity. This is due to characteristics of how the immune system interacts with each particular infectious agent, and those same characteristics make it easier to develop a vaccine that also confers complete, long-lasting immunity. But with other viruses, including a handful of coronaviruses that cause common colds, research has shown that people can develop immune responses but with immunity that does not last long. Consequently, they can develop the same cold more than once in a lifetime.
When it comes to pregnancy, if you have been infected and have recovered from COVID-19, does it mean that you protected against infecting your partner, your children, your newborn baby? Does it mean that you are protected against becoming ill a second time with the same disease? The research is not so clear on this yet. We have touched on this issue in an earlier post, but there has since been an update, namely that a man in Hong Kong who recovered from COVID-19 was found to have been reinfected with SARS-CoV2. While scientists and public health experts are still very much on the beginning of the learning curve on this issue, one possibility that’s emerging is the strength and durability of protection by the immune system may relate to whether or not one actually develops COVID-19 symptoms as opposed to having what doctor’s call an asymptomatic infection. Specifically, it may turn out that having an infection that produces symptoms may give your immune system a bigger boost than getting infected in a way that makes your COVID-19 test positive without making you sick at all.
Contrasting with the finding of the man in Hong Kong is a study by South Korean Center for Disease and Control, revealing that many people who test positive for SARS-CoV2 after recovering from COVID-19 do not have viral particles in them. Rather they have merely pieces of viral RNA, genetic material from the virus, effectively remnants of the virus analogous to dead bodies. This is not the same thing as having full viral particles that are capable of spreading the infection. This study involved people who were testedwith a procedure called RT-PCR. This is a very sensitive procedure that can pick up such low levels of viral genetic material that it designates people as positive, not only if they carry enough virus to be infectious, but also if they have smaller viral loads that are not enough to spread the virus to other people.
Until scientists learn more, if you have made a full recovery after suffering from COVID-19, it means one important thing: First, if you are still testing positive for COVID-19 for weeks or months following your recovery, most likely, you will not spread the disease to others, because probably if there are any virus particles in your body they are not present at a high enough concentration for you to be infectious. On the other hand, especially given the case of re-infection in Hong Kong, you should continue to use reasonable precautions, such as wearing a mask while near your infant and washing your hands before handling him or her.