Outbreak of the COVID-19 virus In November-December 2022 in Thailand, it was clear that There are more outbreaks And the number of deaths increased from 20-30 per day to more than 100 (Department of Medical Sciences reported that Between 26 Nov. and 2 Dec. 2022, 435 samples from Thais and foreigners were found. The proportion of BA.2.75 as a whole increased to 75.4% from 60.1 last week, making BA.2.75 the main strain currently endemic in Thailand replacing BA.5. in this study, the BQ.1 strain was found in 13 people and the XBB strain in another 30 people). increased epidemic There are more people infected with death even though the disease is endemic. therefore making me want to summarize the properties of the COVID-19 virus New strains that are spreading, including the severity of COVID-19. and keeping the public to understand correctly to prepare and protect themselves to be ready and suitable for the current outbreak situation
1. The COVID-19 virus The epidemic came in waves (big or small waves) caused by many mutations in many locations, especially at spike proteins, resulting in many subspecies of omikron. The interesting thing to watch is Omicron substrains BA.2.75.2, BQ.1.1 and XBB because the mutations in this group have the following effects.
l The infection attaches to receptors of human cells in the respiratory tract. Easier and tighter This makes this strain easily “dig” into the cell to multiply quickly. This allows the infection to spread easily and replace the original strain.
l mutations at the spiny protein loci of these strains This allows ommicrons to evade the antibodies (human IgG antibodies that protect against the virus “burrowing” into human cells) caused by infection with the COVID-19 virus. before or a long time ago vaccination As a result, people who have been vaccinated or infected with the COVID-19 virus for more than 4 months do not have high enough immunity to prevent infection with the COVID-19 virus. can reproduce from this new species
l Similarly, commercially produced monoclonal antibody (mAb), including EVUSHELD®, are ineffective against BA.2.75.2, BQ.1.1 and XBB, becoming expired due to mutagenicity or inactivity of antibodies against BA.2.75.2. Spiny proteins of new strains It is not expired because the condition of the drug deteriorates according to the storage of the drug or over time.
l For this reason, it is recommended that mAb be administered in the treatment of this disease in conjunction with other antiretroviral drugs, such as molnupiravir or paxlovid, to achieve a more comprehensive therapeutic effect than mAb alone.
l mutation in the spiny protein position of this group This makes this position poor antigenicity, i.e. it rarely induces IgG immunity in humans (perhaps because immune cells remember only the Wuhan virus spike proteins) under antigenic imprinting. IgG is high enough to inhibit the virus from using the spike protein to “mud” into human cells. This causes humans to be infected with the same species again, even though they have recently been infected and recovered from the disease for a short time.
l In terms of the ferocity of this strain of micron that can cause severe disease Killing human cells or causing a cytokine storm has not been found in these mutants. Therefore, the disease is not severe and can heal by itself in normal people.
So why are there more deaths from new omikron species? From where there used to be 20-30 deaths from COVID-19 per day to more than 100 cases, the likely causes in items 2. to 4. are as follows.
2. The deceased has never been vaccinated against COVID-19. or have never been infected before or incomplete vaccination to the fourth booster dose or the last injection for more than 4 months, resulting in insufficient immunity or sufficient variety against this type of infection when infected The virus will invade long before the body will build up immunity against the invasion of the virus. Respiratory organ damage is thus greater than people with high levels of immunity and are already diverse enough to withstand the invasion of the COVID-19 virus.
3. The deceased has disabilities of various organs. or immunodeficiency disease, especially group 608, very obese and pregnant women If the infection is severe for a while, it will cause disability of that organ and cause failure of breathing or circulatory system more easily and faster than normal people. more complete than group 608
4. The deceased inhaled a large amount of infection and the infection reached deep into the lungs in a short time, such as in the case of a pub. A narrow, poorly ventilated room where many people gathered close together. have a singing Yelling and staying in that place for hours in which the deceased did not wear a mask as well As a result, it can cause pneumonia more quickly because it receives a large number of infections and a cytokine storm can easily cause respiratory and circulatory failure faster.
This group of dead will be the group that helps the COVID-19 virus. Continue to mutate and get new species. and result in the selection of new mutants that are easier to spread naturally causing outbreaks in various ripples As has happened in the past 3 years, or to put it simply, the outbreak of new mutant strains has been wave after wave in the past 3 years, mainly due to the failure to prevent the spread. Airborne spread of infection in people who are infected and have severe symptoms.
For those who wear a hygienic mask in the open air well ventilated If entering a crowded gathering still wearing a hygienic mask Or go into a crowded room or place where the air does not flow It didn’t last more than half an hour. and have been vaccinated with the 4th dose, or have been infected for more than 4 months, will not have a chance to get infected or if you accidentally get some infection will receive a small number of infections and will only get a little sick and recover And being infected again will also stimulate immunity against COVID-19. This group of people will help reduce the spread of COVID-19. and reduce the spread of new mutants in the community as well
Is antiretroviral therapy other than a monoclonal antibody still effective against omikron mutants-substrains BA.2.75.2, BQ.1.1 and XBB?
When the infection has increased mutations in several locations including the spiny proteins, it has become more prevalent, for example, BQ.1.1 from BA.5 or XBB and BA.2.75.2 from mutants. strain BA.2 (BA.2.75.2 evades IgG immunity better than BA.2.75). Will this mutant group remain susceptible to currently available antiviral drugs? In vitro susceptibility study of BQ.1.1 and XBB mutants to remdesivir (an enzyme inhibitor RNA-dependent RNA polymerase [RdRp]) against molnupiravir (RdRp inhibitor) and nirmatrelvir (protease inhibitor). Wuhan/Hu-1/2019 Numerous loci and some mutant loci occur in proteases and also at RdRp remain well susceptible to these antivirals. Or a little better compared to Wuhan, and I personally think that this antiviral drug is also effective against BA.2.75.2 that is currently spreading heavily in Thailand.
Therefore, when anyone knows that they are infected with COVID-19 That person must quickly assess himself while still having green symptoms that Will his disease be so severe that he needs a ventilator? May consult or ask for advice from a doctor as well. (As for people with “yellow and red” symptoms, they must already take antiretroviral drugs.) This antiretroviral treatment approach must also allow the infected person to make a decision in choosing their own medication. If you judge yourself to be at increased risk of violence want to reduce the time of infection So hurry up and decide to take antiviral drugs for treatment. because of the treatment of infectious diseases, especially COVID-19 for the best results and the best value Antiretroviral drugs must be taken as soon as possible after becoming aware of the infection. You don’t have to wait until you have a relapse to fall into the yellow or red criteria and then take antiviral drugs.
Finally, it can be concluded that the Omicron virus will mutate into new strains and spread in waves. Keep going until you get the most infectious mutants. IgG antibodies to the spike protein arising from infection or vaccination do not last longer than 1 year and do not cover new strains that are or will emerge in the future. Therefore, a vaccine must be developed that can induce IgG antibodies to match the mutant spike protein and produce IgG at a high level and grow quickly and last long enough. The current vaccination in Thailand can reduce the severity of the disease if it has been injected for less than 4 months. must be modified to keep up with the mutant infection Otherwise, it will expire faster because the mutant germs locate the spike protein faster. antiretroviral therapy self-assessment with the severity of the disease must be assessed correctly since the infection is known If you want to take antiviral drugs, you need to take them quickly, that is, since you know that you are infected. Preventive measures include wearing a mask, washing your hands, avoiding or not going to slums and poor ventilation for a long time. Including booster vaccination is always a standard way to prevent infection or reduce the severity of disease.
Emeritus Professor Amorn Leelarasamee, M.D.
December 9, 2022