For now, coronavirus reinfection is rare, but the history of other coronaviruses teaches that acquired immunity may decline within three to four years. Then the risk of another infection will increase. They can also be caused by new variants of the virus – says Dr. med. Tomasz Smiatacz. Who is at greater risk of recontamination with SARS-CoV-2? Who Are More Protected Against COVID-19 Recurrence – Vaccinated or Recuperated? He explained in an interview with PAP.
Dr hab. Smiatacz is the head of the Department of Infectious Diseases at the Medical University of Gdańsk, vice-rector for student affairs.
Is SARS-CoV-2 re-infection common? There is something to be afraid of?
Dr hab. med. Tomasz Smiatacz: Currently, it is a very rare phenomenon, and it is also difficult to detect because it requires three well-documented events – first infection, recovery and re-infection. Meanwhile, different criteria for the diagnosis of reinfection and diagnostic tests are used in different parts of the world. Some of the reported reinfections may also be a false positive test result.
So there is nothing to be afraid of?
Not today, but the reason we’re talking about it is that reinfection was very common with other coronaviruses that cause mild upper respiratory tract infections (not including SARS and MERS). They come back in an epidemic form. We suspect that the cause lies in the loss of immunity that naturally occurs some time after the first infection. We are afraid that the human body may react to SARS-CoV-2 in a similar way. This must be monitored urgently, because three to four years after the infection, the immunity may drop so much that the risk of recurrence of the infection may increase significantly.
Is re-infection more common in severely ill people?
There is no simple relationship here, but quite the opposite seems to be. Severe COVID-19 survivors tend to have more antibodies and may therefore have more sustained immunity.
And is the severity of the first infection related to the severity of symptoms in re-infection?
Not necessarily. The descriptions we already have show that, even after severe disease, reinfection is asymptomatic or mild. It is the result of immunity that has already arisen, but whether it will last for two, three or four years, I cannot say.
Can any other factors increase the risk – such as age or co-morbidities?
As for the age, that remains to be seen. Elderly people develop immunity less efficiently and it may fade sooner. However, a much more important factor is the immunodeficiency, e.g. after transplants, with full-blown AIDS or therapy with monoclonal antibodies. Therefore, oncological, haematological and transplant patients will be more susceptible.
What else does or will the threat depend on?
The possibility of the emergence of new virus variants is more dangerous. There is a risk that there will be some that will bypass the acquired immunity. Fortunately, this is not the case with the Delta variant. It has a slightly different structure of the S protein, so antibodies produced after infection with an earlier version or after vaccination bind to it slightly less, but they are still active. At least because of this difference, it is so important to fully vaccinate, i.e. to take two doses of the preparation that requires it.
There has even been discussion about whether to introduce a third dose – a booster. Fortunately, there is no variant yet that would completely bypass the current immunity, and it is rather a question for virologists whether such a virus can arise at all. At the same time, be aware that new virus variants are more likely to be produced where they are allowed to.
Meaning?
It is about places where they can multiply freely. It was not without reason that they emerged in countries such as India, Brazil and South Africa, where access to vaccinations was severely limited.
The Delta variant is more likely than the original version to infect both people who have undergone COVID-19 and those who have been vaccinated?
Antibodies generated after vaccination bind slightly less with the S protein of the Delta variant, but their action still translates into high vaccination efficiency. It must be remembered that there is no perfect vaccine that is 100% effective. It is estimated that the best SARS-CoV-2 vaccines protect up to 95%. before falling ill, so there is some chance that the vaccinated person will become infected even with the basic variant. Today, however, it is mostly unvaccinated people and those who have not been ill before.
The vaccine protects against disease and against infection?
It is important to distinguish between disease and infection. Some infected people will develop COVID-19, but some will pass the infection without any symptoms. Vaccinated people get sick much less frequently, but this does not exclude the possibility of infection and transmission of the virus.
Does some research also show that vaccines are protected against infection?
This is true, but it is extremely difficult to design a test that measures the level of protection against infection rather than against disease. Indirectly, we learn that vaccines clearly reduce the risk of infection, but the risk is not zero. The vaccinated person may not have symptoms, but pass the virus on to others.
Who is more protected against the disease – vaccinated persons or convalescents?
Both groups are protected to a similar degree. Data available in the scientific literature do not indicate significant differences. The question is how long the protection will last and whether any of its types will expire faster.
We hope that immunity will not wear off as quickly after vaccination, but our experience with these vaccines is too short to be able to say this unequivocally. However, it is important that a further booster dose of the vaccine can be given if needed.
So, should both vaccinated and infected people continue to take precautions such as wearing face masks, maintaining social distancing?
Such an asymptomatically infected person may unknowingly become a source of infection for people in the environment – household members or patients in the case of healthcare professionals. Maybe the risk to an individual is not statistically high, but from the point of view of the development of a pandemic, it is important. Thus, both the recovering and the vaccinated as much as possible should continue to use the recommended methods of protection at a time when new infections arise in the environment.
PAP / Marek Matacz
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