The location was specified for 2073 out of 4161 tweets. Users from Algeria, the Netherlands, Denmark, Argentina, Cambodia, Mongolia, Cabo Verde, Abkhazia, LNR, San Juan y Martinez, Singapore, Bosnia and Herzegovina, Sweden, Uzbekistan left 1 tweet each. Users from Ecuador, Belgium, Greece, Bulgaria, Armenia, Lithuania, Bermudes, Portugal, and the Slovak Republic left 2 tweets each. Users from Spain, Italy, Thailand, Canada, and Switzerland left 3 tweets each. Users from Austria, Turkey, Moldova left 4 tweets each; from Fiji, Syria – 5 tweets each; from Cyprus, Estonia, France, Australia, Latvia, and the Republic of Korea – 6 tweets each; from Poland, Serbia – 8 tweets; from Finland – 9 tweets; from Donetsk, Israel, Japan – 10 tweets. The countries with highest number of tweets are shown in Table 1.

Fig. (1). Terminological map of the ideology of anti-vaxxers (based on materials from the Sevpolitforum.info forum).

Most users are Russians. 35.56% of Russian users' tweets are from Moscow and 10.88% are from St. Petersburg. So 46.44% are from two Russian capitals (almost half of all Russian users' tweets). The share of all post-Soviet republics was 12.01%. The expressed earlier hypothesis that the authors of Russian-language tweets are mainly Russians was confirmed.

The tweets were analyzed by topic. Expert analysis of the texts (Methods and Materials) revealed nine central sub-topics related to attitudes towards PCR tests and PCR testing: 1) Test expiration date; 2) Passing the test; 3) Test result; 4) Test cost; 5) Border control (using a test to control people crossing the border); 6) Control inside the country; 7) Test reliability; 8) Conspiracy theory; 9) Fake tests. Tweets that had not been included in the listed above sub-topics made up the Miscellaneous group.

Tweets were analyzed statistically in each sub-topic (theme). The analysis included counting the total number of tweets (including retweets) and the number of original tweets. Fig. (2) shows the ratio of the total number of tweets (including retweets) with the PCR keyword by sub-topic as a percentage of the total number of tweets.

The prevalence of tweets on the sub-topic “Test expiration date” is due to the fact that in order to combat the omicron strain, Rospotrebnadzor decided to limit the validity of the PCR test from 72 to 48 hours [36]. So, many tweets include retweets of official announcements about the reduction in test validity with user comments. The number of original tweets on the sub-topic “Test expiration date” was only 18.67 percent. Therefore, the sub-topic “Test expiration date” is “short” and not suitable for long-term consideration. Thus, the hypothesis about the presence of “short” topics in the discussion is confirmed.

Fig. (2). Total number of tweets (including retweets) with the PCR keyword by sub-topic as a percentage of total tweets.

Fig. (3). Number of original tweets (excluding retweets) with PCR keyword by sub-topic in percent of the total number of original tweets.

Fig. (3) shows the ratio of the number of original tweets (excluding retweets) with the PCR keyword by sub-topic in percent of the total number of original tweets. The discussion of passing the test and test results dominated in the original tweets.

Many tweets in the sub-topic “Test expiration date” were related to the fact that Rospotrebnadzor, in order to combat the highly infectious omicron strain, reduced the validity of the PCR test [37]. It has raised the concerns that people who take the test could receive its results after the expiration date.

People discuss the conditions for taking the test in the sub-topic “Passing the test”. They report about passing the test and the anxiety before taking the test. Users share information about their test results (positive or negative), often conveying their emotional state in the sub-topic “Test result”.

There are significant number of tweets in the “Test cost” sub-topic related to the high cost of PCR tests, including suggestions that the high cost is associated with profit. Proposals to reduce the cost of the test are being discussed.

Users discuss the conditions for passing the test when crossing the border in the “Border control” sub-topic. Users discuss the restrictions inside the country in the “Control in the country” sub-topic.

Users discuss incorrect test results in the “Test reliability” sub-topic. Some users try to explain the reasons for the inaccuracy of PCR testing. Some users have a negative attitude towards the reliability of PCR testing. Based on references to authoritative sources and scientific terminology, some users try to convince the audience that the tests are wrong.

Users have raised concerns that many commercial companies are benefiting from PCR testing in the sub-topic “Conspiracy theory”. Some users believe that PCR testing is an attempt to collect genetic material or a way to infect people with the coronavirus. They even think that raw materials are used to produce new strains. They discuss the sale of fake PCR certificates in a small sub-topic “Fake tests”.

Examples of tweets reflecting the mood of users in the discussion of PCR testing for selected topics and sub-topics are shown in Table S1.

To develop and implement approaches for creating principles of the Strategy, the sub-topics “Test reliability” and “Passing the test” were chosen. The criteria for selecting sub-topics were as follows: 1) insufficient awareness of the population about the discussion object (PCR testing); 2) non-political nature of the discussion; 3) a relatively high number of messages that contradict each other (PCR results are correct or incorrect); 4) the “long” nature of the topic (the topic is not due to some short-term event).

As the first principle, we propose an explanation of the scientific meaning of the terms that people use often without understanding their semantic content. Sometimes users do not understand the terms’ ambiguity. While the contexts determine one or another meaning of the term (“Definition clarification principle”).

To illustrate and further implement this principle, the sub-topic “Test reliability” has been chosen. As can be judged from the content of tweets devoted to PCR testing, Russian-speaking Twitter users often do not even know the decoding of the term. The meaning of the term is clear only to specialists. Only 2 out of 140 tweets contain a transcript of the abbreviation PCR (1.42%), for example: “PCR is polymerase chain reaction testing”.

Sometimes people express a desire to know what a PCR test is:

“...explain to me what PCR is in human words”;

“I thought PCR showed whether the microbes on the plate multiplied in a day, or in the machine in less than a day. Nothing is clear, but very interesting, thanks for telling”.

To clarify the scientific meaning of the term it is necessary to refer to scientific sources. Here is an example of explaining the essence of PCR testing:

“PCR testing makes millions of copies of a specific sequence or sequences in the genetic material present in the sample allowing for detection of a much lower initial viral load. These copied sequences can then be used to diagnose a patient, either by their presence (positive) or absence (negative). In the case of COVID-19, the genetic material is comprised of Ribonucleic Acid (RNA), which is relatively fragile, as opposed to Deoxyribonucleic Acid (DNA), which is far more stable” [38].

The dictionary by Merriam-Webster contains the following definition for polymerase chain reaction: «an in vitro technique for rapidly synthesizing large quantities of a given DNA segment that involves separating the DNA into its two complementary strands, using DNA polymerase to synthesize two-stranded DNA from each single strand, and repeating the process — abbreviation PCR [39].

We tagged a post on Twitter with an attempt to explain the essence of PCR (we used sources [40-42] for the formulation):

“What is PCR? The nose sample contains an extremely small amount of coronavirus RNA. With the help of PCR (polymerase chain reaction), this RNA grows by multiple doubling with the help of the polymerase enzyme so that the device can understand whether there is a virus or not”.

“What is #PCR? Nose sample has #coronavirus RNA if it's already there. This RNA is extremely scarce. With the help of PCR (polymerase chain reaction), this RNA is multiplied by multiple doubling with the help of the polymerase enzyme so that the device can understand whether there is a virus or not”.

We have developed the second principle of comparing user and scientific meanings of terms considering the contexts of their use (“The principle of matching the term meanings”). On the example of the chosen sub-topic “Passing the test”, we will try to find out the everyday understanding of the term “primer”. There are few tweets containing this term without understanding its meaning.

“Okay, thanks for the fact that at least on modern methods of genetics we calculate all sorts of PCR and write primers, at least something useful”.

“PCR shows the presence of a “primer”. Short section of DNA. How to find a nut, to assert that there is a whole Mercedes around the corner. The latest model, serviceable, with a full tank, a running engine and a driver behind the wheel. Not even a detail. Just a nut. Almost anything”.

Primers are involved in the polymerase chain reaction, which proceeds under the action of polymerase enzymes. DNA and RNA polymerases synthesize DNA and RNA molecules, respectively, mainly by complementary copying of parent DNA or RNA strands [43].

For the polymerase to multiply the available nucleic acids incompletely, scientists point out the enzymes which fragment has to be reproduced using primers. These are small sequences (pieces) of DNA that stick to a site chosen by researchers on a copied strand. Two primers on both sides limit the area to be propagated. A primer is an artificially synthesized sequence of nucleotides.

The site for copying during PCR testing for coronavirus is chosen so that it: 1) is present only in the genome of coronavirus; 2) was conservative enough not to mutate constantly; 3) differed from similar places in the genomes of related viruses [44].

The Merriam-Webster Dictionary includes the following definition of a primer: “a molecule (such as a short strand of RNA or DNA) whose presence is required for the formation of another molecule (such as a longer chain of DNA)” [45].

The MeSH Thesaurus (PubMed) has Subject Heading “DNA Primers”: “Short sequences (generally about 10 base pairs) of DNA that are complementary to sequences of messenger RNA and allow reverse transcriptases to start copying the adjacent sequences of mRNA. Primers are used extensively in genetic and molecular biology techniques”. Year introduced: 1994 [46].

Therefore, statements that PCR shows the presence of a primer as a fragment of the genome of a coronavirus (or another virus) are fundamentally wrong. We formulated the following tweet:

“Some say that the #PCR test detects a primer, a piece of DNA out of nowhere. Nonsense. Primers tell the polymerase which piece of #coronavirus RNA to replicate. And this fragment is chosen wisely, so that it is “unique””.

We proposed the principle of contextual comparison of the widespread mass user and scientific meanings of a term as the third one (“The principle of judgments’ comparison”). To implement this principle, the sub-topic “Test reliability” was chosen.

There were analyzed 164 tweets in this sub-topic to highlight the terms presenting the conflicting opinions. The judgment about the falsity of PCR tests was the most common (44.51%, 73 tweets). Here are some of the most characteristic phrases from the tweets:

“PCR tests are completely deceptive and designed to detect the common cold”.

“PCR tests give more than 50% false results, do not detect the virus even in people with obvious signs of the disease and detect it ... in plants!”.

“PCR tests do not distinguish covid from flu!”.

“PCR false positive rate is almost 80% because PCR is not a diagnostic tool (as its inventor said)”.

However, some tweets reported inconsistencies between the test result and the condition or diagnosis:

“I went hunting with a friend, he and his wife had symptoms, they passed the PCR and showed negative. And now have handed over on antibodies long and short. He is still sick, but his wife has already recovered”.

“There are antibodies. PCR showed nothing”.

A number of tweets gave an explanation for the inaccuracy of the tests, indicating that the accuracy of PCR depends on the procedure itself and time (23 tweets). Here are some of the most characteristic phrases from the tweets:

“... regarding PCR tests, they work exclusively in the early days of infection”

“... PCR is informative to take in the early 3-5 days. Then the virus goes down. From the pharynx, a smear will not show anything. And it is forbidden to take a deeper swab”

“... Although the PCR was negative, most likely the smear was taken late, when the virus went down into the lungs.”

“The PCR test gives false negative results, because if the virus multiplies just 1 cm lower than the cotton swab touched, its DNA will not be in the sample ...”

Some messages contain information about the reliability of test: “Will #PCR tests detect new strains of coronavirus?”

We gave the answer: “Because those parts of the #coronavirus that mutate the least are chosen for the reaction. These areas are not on the spikes, but between them. And it is the spikes that mutate quickly”.

We proposed “The principle of visual promotion” of scientific knowledge (as the fourth principle). The illustrations explaining the principles of DNA replication are very complex (Fig. 4).

Fig. (4). The replication of DNA. Replication occurs by means of the partial unwinding of the two strands accompanied by the synthesis of a new strand complementary to each of the originals [47].

Fig. (5). The replication of DNA.

We posted a tweet (”#PCR test creates conditions for the multiplication of #coronavirus RNA so that the device can detect it”) for which we made the following picture Fig. (5) based on the work of Safiabadi et al. [48].