Under what diagnoses COVID-19 disguise in Tatarstan?

The new coronavirus infection may be hidden in official statistics, including in the column “acute upper respiratory tract infections”

Under what diagnoses COVID-19 disguise in Tatarstan?
Photo: Ilya Repin

Official statistics on the incidence in Tatarstan has shown an inexplicable increase in acute upper respiratory tract infections — most significantly in June 2020, almost twice as much as in the same month a year earlier. Realnoe Vremya found out: it is possible that this increase has been due to Covid-19. This means that the real figures of morbidity in the republic may be much higher than those announced daily by the Tatarstan ministry of healthcare, which is bound by federal standards.

Atypical June

The analytical service of Realnoe Vremya has studied the reports of Tatarstan state statistics service on population morbidity for the first six months of 2020 — and has found a strange increase in the number of acute upper respiratory tract infections. The sharpest jump occurred in June relative to the same period in 2019 and 2018. For example, on the equator of this summer, 47,002 Tatarstan citizens were ill with such infections, while June 2019 showed 26,827 cases, and June 2018 — 23,608.

However, the statistics for the half-year are quite rosy: an increase in the incidence for the six months in the aggregate was not found. There is even a slight decrease — by 3,7 percentage points in absolute terms and by 4,2 percentage points in terms of 100,000 people. The thing is that in April and especially in May, the incidence was significantly lower than in previous years. This is explained simply: while people were in self-isolation, they turned to doctors less often (and therefore did not get into the statistics), and they were catching all sorts of viral respiratory infections much less often than usual. How can one catch, going only to a store and observing the strictest mask and glove regime?

By the way, the statistics of he decreasing number of all infections by a record 22% in six months was given back in July by Lyubov Avdonina, the deputy head of Rospotrebnadzor Department in the Republic of Tatarstan. Then she said that the need to wash hands, wear masks and self-isolate reduced the incidence of intestinal infections by 36%, enterovirus infections — by 30%, chicken pox — by 25%, salmonellosis — by 14%, tuberculosis — by 12%.

Thus, even the almost 100% increase in the incidence of upper respiratory tract infections in June could not significantly spoil the overall statistical picture of the half-year. But it raises the question: hasn't the coronavirus, the peak of which was observed in Tatarstan shortly before that, “got into” this seemingly harmless graph?

“There is a high probability that it was Covid-19"

Khalit Khayertynov, chief extraordinary specialist of the ministry of healthcare of Tatarstan on infectious diseases, did not confirm this hypothesis definitely in an interview with Realnoe Vremya but claims that, most likely, it is true:

“That seems to be the case. I can't say for sure, but usually the rise in the incidence of viral respiratory infections is observed in the cold season. Such growth is illogical for May or June. It is explicable in September-October and inexplicable for the warm months of the year. Given the fact that the increase in the incidence was noted just during the coronavirus epidemic, it was most likely associated with this infection. Because when in the summer there is an increase in the incidence of viral respiratory infections, then immediately there are doubts that these are some classic diseases. There is a high probability that it was Covid-19.

Usually, a rise in the incidence of viral respiratory infections is noted in the cold season. Photo: Oleg Tikhonov

According to Khalit Saubanovich, the usual average summer is more likely to give a surge of intestinal or natural focal infections (for example, hemorrhagic fever with renal syndrome) than acute respiratory diseases. By the way, the June statistics on intestinal infections with an unidentified pathogen is really pleasing to the eye: only 140 registered cases. In June 2019, there were 549, and in 2018 — 506. Apparently, we should thank closed eating establishments and general “isolation background” of the beginning of the summer for such a sharp improvement.

Under what diagnoses coronavirus disguise?

The infectious diseases specialist explains how coronavirus is “disguised” under other types of respiratory infections:

“Coronavirus may occur with upper respiratory tract infection, but without pneumonia, or it may occur with pneumonia. Therefore, in cases where there is no pneumonia and the pathogen is not isolated in the laboratory, doctors diagnose viral respiratory infections. That is, in the case of coronavirus in the form of viral respiratory infection in the absence of isolation of the pathogen, this will be concealed as viral respiratory infections.

According to Khayertynov, the RNA of the virus is not isolated in all cases of the disease. Coronavirus diagnosis is performed by PCR and computed tomography. But there are also nuances.

“There are two ways of coronavirus disguise — the first is when the virus is isolated, and then the diagnosis is “coronavirus infection confirmed by virus isolation”. The second option is when the diagnosis is made, but it is unconfirmed, without isolation of the virus. This occurs when there are clinical manifestations (for example, decreased saturation or shortness of breath), there are changes on CT scan that are characteristic of this infection. In this case, we diagnose unconfirmed coronavirus.

And there is no contradiction in this: the thing is that doctors can make a completely confirmed diagnosis of COVID-19 only if there are results of laboratory tests. Only on the basis of the clinical picture the diagnosis made in the case of, for example, influenza and some forms of adenovirus infections. All other respiratory viral diseases caused by two hundred different pathogens (including coronavirus) are clearly diagnosed only in the laboratory.

Coronavirus diagnosis is performed by PCR and computed tomography. Photos: gkb81.ru

The virus disappears by the tenth day of the disease

According to the infectious disease specialist, it is very difficult to make a diagnosis unambiguously if there are clinical manifestations, but there are no changes on the tomogram, and the virus is not isolated in smears. This may well be COVID-19, which occurs in a mild respiratory form — and then the person does not get to the dispensary hospital, does not get PCR tests, and is very likely to fall into the very column that we are interested in.

Under the general name “acute upper respiratory tract infections”, there hides a whole layer of symptomatic diseases — this is everything that is associated with a runny nose, nasal congestion, and sore throat. These include, for example, rhinitis, rhinopharyngitis, nasopharyngitis, laryngitis.

The PCR method is crucial in diagnostics for Russian doctors. It will be positive from the first days of the disease, unlike the test for antibodies, which begin to be produced on about the fifth day of the disease. However, there are also false negative results of the PCR test. Khalit Saubanovich found it difficult to give official figures on how often such errors occur — there are different data that vary greatly from source to source.

To a greater extent, such tests are aimed at establishing the very fact of an infectious disease in a person. Photo: Maksim Platonov

“As for detecting antibodies, it has an auxiliary, not the main significance. To a greater extent, such tests are aimed at establishing the very fact of an infectious disease in a person. There are different classes of antibodies. There are immunoglobulins M, and there are immunoglobulins G. Immunoglobulins M are produced first, and if these antibodies are detected, this indicates an acute phase of the disease. If the process is already old, more than two weeks have passed, then there should already be immunoglobulins G, and this indicates an infection.

By the way, the virus itself, according to the doctor, disappears in humans by about the tenth day of the disease, so with a mild form of the disease, about two weeks is enough for a person to fully recover.

This may be due, for example, to the fact that antibodies (including class M) to Covid-19 in humans are detected during analysis, but the RNA of the virus is no longer present. He is still ill, but already in the inactive phase, so the PCR test does not show the presence of the virus, which means that it is not included in the coronavirus statistics.

By Lyudmila Gubaeva
Tatarstan