India On the brink of third wave of Covid 19 due to Omicron variant
Dr Asha N Shah M.D (Medicine)
Professor of Medicine, GCS Medical college, Ahmedabad
Introduction
Omicron is the 15th letter of the Greek alphabet and is derived from the Phoenician letter ayin. The World Health Organization started naming the variants after Greek letters and they jumped two alphabets Nu and XI to avoid public confusion and stigma and named it omicron.
On 26 November 2021, WHO designated the variant B.1.1.529 a variant of concern, and also named it Omicron. As per them it is already circulating in 77 countries but it is very much possible that it is present in other countries as well. As per the latest news it is present in 90 countries.
Origin of Omicron
Scientists think that this variant evolved from a strain that was circulating in mid-2020, in the intervening months there has been no trace of all the intermediate versions that scientists would have expected to find as it mutated into its current form.
Various theories were put forward to explain the origin of omicron.
Animal origin
It’s possible that the mid-2020 strain infected some unknown animal population, evolving as it spread among that animal population and has just recently spilled back over into humans.
But this hypothesis is unlikely as there would have been signs of the animal’s genetic material in the genome which was not evident, and instead there’s an insertion of human RNA that suggests that it was evolving in a human.
Spread in unmonitored country
Another theory is that the mid-2020 strain started circulating in a location where there was not a lot of monitoring like in African country, then that would have enabled the virus to evolve without being detected and by year 2021, it must have picked up enough mutations and it became much more transmissible and then exploded onto the scene at that point. The point against this hypothesis is that once a variant reaches South Africa, at least, it is likely to get identified as there are many labs to conduct the required tests. Omicron also has peculiar characteristics on PCR which would have been picked up.
Evolution in immunocompromised person
The virus might have mutated as a result of an untreated HIV infection in the patient. In such instances, the person’s immune system is still strong enough to prevent the coronavirus from killing the person. However it’s not strong enough to clear the virus completely. So the virus remains inside the person, continually reproducing. With each replication, there’s a chance it will acquire a mutation that makes it better at evading the person’s antibody-producing immune cells. Scientists demonstrated this by retroactively analyzing a series of coronavirus samples of 6 months period from HIV positive women whose HIV status was uncontrolled and it took 7 months to clear virus from her body and in that time multiple mutations took place in her body and after so many mutation the new strain emerged which is now termed omicron and is a variant of concern and spreading throughout the world. So this HIV positive woman became a source for creating a lot of new variants and the dreaded omicron. So immunocompromised individuals are very important or they are the key to end the pandemic as per the opinion of leading scientists.
The covid vaccines may not be effective for people who are immuno-compromised for reasons other than HIV,like individuals with cancer or organ transplant recipients who are taking immuno-suppressing drugs to keep their bodies from rejecting the transplant etc. Researchers found that these patients don’t have measurable levels of anti-coronavirus antibody in the blood even after covid vaccinations. Most countries around the world have immunocompromised individuals. HIV patients need to be treated and well controlled on their drugs and all immunocompromised individuals must receive third dose of vaccines.
Spread of Omicron
figure courtesy CNN
Transmissibility of omicron
In late November, South Africa’s National Institute for Communicable Diseases (NICD) determined that R of omicron was above 2 in Gauteng and it was well below 1, when Delta was the predominant variant. They believed Omicron can infect three to six times as many people as Delta, over the same time period. Some research in UK shows that R may be 3 to 5 for omicron. While researchers in Canada claimed that omicron could transmit 70 times faster than Delta. One thing is sure. It is very highly transmissible. How well the variant spreads might depend on factors such as vaccination and previous infection rates, vulnerable population, age of population etc .Researchers found that this variant proved fully resistant to neutralizing antibodies from most of the people they tested, either people who had either received two doses of an mRNA vaccine or the ones who recovered from COVID-19. As per the researchers, two doses of the mRNA (Pfizer) vaccine were 33% protective against overall infection but 70% effective in preventing severe complications, including hospitalization .This research shows that no one is safe So the infection can occur in these individual who had neutralizing antibodies but it does not mean that immune responses triggered by vaccination and prior infection will offer no protection against the variant. Immunity studies suggest that modest levels of neutralizing antibodies may still protect people from severe forms of COVID-19 or death. Other aspects of the immune system, particularly T cells, may be less affected by Omicron’s mutations than the antibody responses.
According to the imperial college London study which involved large number of patients (around 2 lakh) ,Omicron has the capacity to elude protection from previous infection or inoculation. A two-dose vaccine gives 20% protection against Omicron, which is in line with natural immunity. A third dose (booster dose) increases the Covid vaccine’s efficacy against Omicron to up to 55–80% in symptomatic cases, the study said, underlining the importance of booster shots. This study involved AstraZeneca and Pfizer vaccines. Unvaccinated people previously infected with Delta have no protection against omicron. They also found that omicron affected young population (18–29 years)
Incubation period appears shorter than other variants and that is why it is spreading so much faster. As per WHO ,it is spreading faster than any previous variant.
Symptoms
Symptoms of omicron are no different from infection with other variants. Mild fever, throat irritation, Runny nose, Sneezing, Body ache, fatigue, Night sweats. Two unusual symptoms that have appeared recently are nausea accompanied by vomiting and loss of appetite, to red and purple bumps on fingers and toes, which could induce pain and itchiness or skin rash. Loss of taste and smell is less common. Lung involvement appears to be less common and less severe. It replicates faster in upper respiratory tract. Symptoms differ between unvaccinated and vaccinated individuals. Vaccinated individuals have milder symptoms than Delta and most hospitalizations are unvaccinated patients but the illness is still new and lot of data is needed. Imperial college of London study shows that it is not milder than Delta. The study also shows that the risk of reinfection with Omicron is five times higher than it was with Delta and also that protection afforded by a past Covid infection is as low as 19% against Omicron.
Who opinion
AS per WHO update on 26th November it is not yet clear that Omicron transmissibility or severity is more compared to other variants including Delta and they also said that all variants causes severe diseases in vulnerable population and this we have observed too. There is evidence that people previously infected with covid are more likely to be affected or reinfection is seen. Vaccine affectivity is reported to be same for mild cases which can occur but effective for severe diseases and death and PCR tests are effective for diagnosis and it was mentioned that the currently available treatment like IL6 inhibitors or steroids etc will be effective to treat severe disease. But more studies are underway which will give us more clear idea .All the precautionary steps should be continued. But WHO has declared it as variant of concern .By definition that means either of the things are true, there is increase in transmissibility or detrimental change in COVID-19 epidemiology; OR increase in virulence or change in clinical disease presentation; OR decrease in effectiveness of public health and social measures or available diagnostics, vaccines, therapeutics
CDC opinion
As per CDC (Center for disease control USA) on 20th December,
Infections with the recently identified Omicron variant of SARS-CoV-2, the virus is exponentially increasing in multiple countries. Increases in infections are most likely due to a combination of two factors:
1) Increased transmissibility
2) The ability of this variant to evade immunity conferred by past infection or vaccination which is called immune evasion or escape.
The Omicron variant was estimated to be in 58.6% of the covid cases as of Dec 25 in USA, according to the data from the US Centers for Disease Control and Prevention (CDC). First known case in the United States identified on Dec 1, in a fully vaccinated person who had traveled to South Africa.
Though the exact contribution of each of the two factors is not known, In vitro studies have demonstrated that there is a substantial degree of immune evasion. At present, studies suggest Omicron infection might be less severe than infection with prior variants; however, reliable data on clinical severity are needed .Even if the proportion of infections associated with severe outcomes is lower than with previous variants, probability of huge increase in number of infections is more and therefore, the absolute numbers of people with severe outcomes could be substantial. In addition, demand for home or ambulatory care, supportive care for treatment of mild cases, and infection control measures, quarantining exposed individuals, isolation of infected patients could take a toll on the healthcare system.
People infected with omicron variant of may have increased immune protection against delta, a new study from South Africa says. As a consequence, omicron may displace delta. This is a small study and more data are needed.
Diagnosis of omicron
The Technical Advisory Group on SARS-CoV-2 Virus Evolution (TAG-VE) is an independent group of experts who have mentioned that Current SARS-CoV-2 PCR diagnostics continue to detect this variant. Several labs have indicated that for one widely used PCR test, one of the three target genes is not detected (called S gene dropout or S gene target failure) and this test can therefore be used as marker for this variant, pending sequencing confirmation. Using this approach, this variant has been detected at faster rates than previous surges in infection, suggesting that this variant may have a growth advantage. S-gene Target Failure (SGTF) is a marker for identifying Omicron cases. Many laboratories in our country don’t test for s gene. Maharashtra government has asked RT-PCR labs to use S gene drop detection kit for early detection of Omicron, even before genome sequencing. It should be made compulsory across country because genome sequencing takes couple of days and also done in select places and as the cases will increase it will not be possible to do it for all cases. At present, in India genome sequencing is done only in select category of patients. Korean scientists have claimed to have developed molecular diagnostic technology that can detect the Omicron variant in just 20–30 minutes and will publish the reports and would be helpful for diagnosis of large number of patients.
Omicron situation in India
The total cases of coronavirus variant Omicron has reached almost 1000(961 to be precise on 30th December). It has now spread to 22 states in the country. Delhi has the highest Omicron cases with 263 cases, followed by Maharashtra with 252 cases. Gujarat has 97 cases, while Kerala and Telangana have reported 65 and 62 cases respectively. Many people are tested positive who has no travel history suggesting probable community transmission. It is confirmed by health authorities in Delhi.
So in India the same scenario is likely to happen as seen in the second wave. Health system is likely to be overburdened all over the world and more so in India as this variant is likely to be dominant variant now. The Delta variant cases were on significant decline in our country but now sudden rise has begun and it is very much likely that this rise is going to be exponential with dominant omicron variant.
As per mathematical model of IIT, the prediction is that our country might witness a peak in Omicron cases on January 27, 2022 with either of the two scenarios likely to happen. With a ‘pessimistic scenario’ with the daily tally of infections at 1.50-lakh cases, the wave could subside completely by March 28, 2022.(a ‘pessimistic scenario’ is one in which all the people that took the vaccines lose their immunity). In an ‘intermediary scenario’ (where 30 per cent of the vaccinated people retaining immunity), the country could witness about 1.30-lakh cases a day. . The third wave of Covid-19 is expected to peak in early 2022 but would be milder than the second wave, according to National COVID-19 Supermodel Committee .No data on prediction on hospitalization is available and exact number of infections also may be difficult to identify. As the cases start increasing, many patients are not likely to be detected as they may be asymptomatic. It is observed in many countries that number of positive cases does not correspondingly suggest increased hospitalization. That is why the illness is thought to be milder. That statement should not give us a false sense of security. Vulnerable population will still be at risk. Virus can further mutate into more virulent form and we have witnessed worst outcome in unexpected patients in second wave.
Conclusion
As per the researcher from John Hopkins University, all of us are likely to have encounter with omicron if we are having any interaction in the society. Best way to encounter it is being fully vaccinated. The scientists all over the world agree that it is going to be a problem. More data are needed to know the exact proportion of it. At present Delta and Omicron both variants are circulating all over the world. Without proper investigation, it is difficult to diagnose what variant is responsible for illness. Unvaccinated or partially vaccinated people and children who are not vaccinated in country like India are more vulnerable. Vaccines alone cannot prevent transmission. It has to be all other very important measures like masks, distancing and ventilation. It is said to be causing milder illness but we have to remember that it is very highly transmissible. As a result third wave may be a tidal wave but will be over also fast. Just when people started becoming complacent, the threat has come with a bang. Bright side of it is that almost all people getting infected with a milder variant and getting herd immunity and ending pandemic but the down side is that it might come with a cost.
References:-
https://www.npr.org/sections/goatsandsoda/2021/06/28/1011043650/the-key
https://www.newindianexpress.com/nation/2021/dec/18/omicron-triggered-third-wave-to
https://www.nature.com/articles/d41586-021-03614-z.
ttps://www.deseret.com/coronavirus/2021/12/17/22841186/omicron-v.
https://www.cdc.gov/coronavirus/2019-ncov/variants/omicron-variant.html.
https://www.gavi.org/vaccineswork/how-do-symptoms-omicron-differ-https://www.imperial.ac.uk/news/232698/omicron-largely-evades-immunity-from-past/
