COVID-19 Breakthrough Infection: Why Don’t We Care

Let’s start with a few important points. First, with COVID-19, neither past infections nor complete vaccination can prevent subsequent infections. There are two different terms used to describe the situation. A secondary infection in a person who has been confirmed to have been infected in the past is called a “reinfection”. However, infections in vaccinated individuals are called “breakthrough” infections. This interesting name is given because it is probably the “breakthrough” of pathogens that can jump over immune barriers.

Second, is it possible to stop future infections? The answer lies only in the scenario of “sterilizing immunity”. This is a type of immunity, once developed, ready to cleanse pathogens when in contact with an immune host. However, the development of this type of immunity depends on several factors, including the host’s immune system, time since last exposure and / or vaccination, route of transmission, incubation period of pathogens, and amount of viral exposure. There is no true bactericidal immunity. Some diseases, such as smallpox (eradicated in 1980) and measles, are approaching the development of such immunity. But even those illnesses have been reported to have some reinfection.

Third, natural infections, and in principle most pathogens, are more likely to provide stronger and longer-term immunity than vaccines. We know that a single infection with measles provides immunity and protection for almost a lifetime. However, when measles is vaccinated, the preventive effect is about 85%. Therefore, a second dose of measles vaccine is recommended. This makes it about 95-98% effective, but not 100% preventative.

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Fourth, the level of immunity is also affected by the route of transmission. SARS CoV2 is primarily a mucosal infection, and immunity and defense against this type of infection is always weak and weak. Respiratory viruses, such as SARS-COv2, which are transmitted through the mucous membranes of the nose and throat and are prone to mutations, are unlikely to provide bactericidal immunity.

Fifth, and most importantly, the use of the term “breakthrough infection” is misleading and not entirely appropriate. It is widely known that most SARS CoV2 vaccines, including those currently used in India, have no evidence to reduce infection. There is consensus that vaccines prevent moderate to severe illness and hospitalization. To date, only mRNA-based vaccines (Moderna and Pfizer-BioNTech) are known to be temporarily protected from infection and infection. And even protection from infection and reduction of infection declines rapidly after 3 months. The role of the non-mRNACOVID-19 vaccine in prophylactic infection has not been proven and is unknown. Therefore, calling SARS CoV2 infection in a fully vaccinated person a “breakthrough infection” tests a very well-performing student in class V for a class VIII syllabus (he or she does not work well). , Similar to claiming next. That she / he is not a good student. Obviously, it’s the wrong measurement tool. The term “breakthrough infection” should not be used in the context of the COVID-19 vaccine, at least for the two major COVID-19 vaccines used in India.

Vaccine performance should be measured against what they are trying to protect. Most vaccines, whether COVID-19 or other vaccines included in the childhood vaccination program, can be classified in the group of vaccines that provide “functional immunity or protection”. This essentially means as much protection as possible against harmful consequences, and the agreed cutoff (COVID-19 long before the first vaccine of COVID-19 was granted an emergency use permit). Efficacy is much higher than agreed at 50%), such as moderate to severe illness.

The persistence of immunity depends on the disease. What we know is that antibody levels drop over a period of time. However, certain types of cell-mediated immunity continue. Regardless of all of these, you are in better health against subsequent infections than when you are not vaccinated. This also applies to SARSCoV2.

SARSCoV2 is the 7th coronavirus It has been detected that it is infected with humans. The first four coronaviruses (OC43, 229E, NL63, and HKU1) caused only mild illness. Studies of these coronaviruses have shown that immunity to them is reduced over a period of time and reinfection is common.

Protection against immunity and disease depends on many factors and complex interactions. Therefore, a simple approach does not help. There is no doubt that scientists and vaccine researchers will do everything necessary to ensure that we are better protected and will continue to work. With the availability of mucosal vaccines, we can expect a slight increase in protection from infection, but the risk of infection still continues.

The key at the individual level is to be vaccinated with an age-appropriate country-recommended vaccination schedule. Then follow the recommended basic preventive approach. High-risk individuals need to be more careful. Do not bother to test for antibodies.

However, from the perspective of health policy makers and epidemiologists, it has some usefulness in the study and understanding of infectious and reinfectious diseases in vaccinated and previously infected individuals. Such data provide useful insights for designing vaccination schedules and other preventive strategies for the future.

The next time someone mentions “reinfection” or “breakthrough infection” in the context of COVID-19, say “it doesn’t matter at the individual level.”

(Dr. Lahariya is a primary care physician specializing in infectious diseases and vaccines. He is the founding director of the Foundation for a Human-Centered Health System in New Delhi. He tweeted at @DrLahariya)