Understanding Covid surge: ‘None of the newer Omicron sub-variants appears to be more virulent’

why? Dr. Lancelot Pinto He is an advocate of collaborative self-management for chronic respiratory diseases and works to empower patients to better manage their illnesses in collaboration with their physicians. A firm believer in preventive medicine, reducing the need for hospitalization in chronic respiratory diseases is the focus of his respiratory medicine practice. He specializes in the treatment of sleep apnea, insomnia and other sleep disorders with the aim of preventing complications such as high blood pressure and heart disease that are often a consequence of such disorders. He also specializes in the management of chronic obstructive pulmonary disease (COPD).

Maharashtra is seeing a daily escalation of Covid-19 cases. On Thursday, the state reported 5,218 cases — the highest number in a single day since February. Active cases in the state stood at 25,317 – 27.58 per cent of the total number of cases in India. Although the severity of the infection is moderate with 95 percent of patients often asymptomatic, public health officials expect a further rise in cases, indicating a “fourth wave.”

We are seeing a new surge of Covid-19 cases in many urban centres. Is this being triggered by a new sub-variable of Omicron? What does the data show?

Altogether 99.6 percent of samples uploaded from India to the GISAID registry within the past four weeks were from the Omicron variant, including sub-lineages. BA.2, referred to as ‘disguised Omicron’ (lacking a deletion at position 69/70 in the S protein) appears to replace existing strains, and INSACOG reports that this is the predominant strain across the country. The BA.2.38 subvariate from Mumbai and Pune has now been reported to be the dominant strain based on sampling and is assumed to be the stress driving the current rise. New subspecies and potential variants were always expected, based on our understanding of viral transmission and evolutionary dynamics, and this was not surprising. Reassuringly, none of these new sub-variables appear to be more virulent.

Data from Maharashtra show that BA.2.38 became the dominant sub-variant of the Omicron strain in Mumbai. What are the characteristics of this sub-alternative?

The sub-variant, similar to other Omicron strains, appears to evade immunity provided by previous vaccines and infections. This is why we see a large percentage of sudden injuries and returns. There is data to suggest that the sub-variable may be more transmissible, which explains the current rise. However, vaccination and previous infection seem to continue to protect against moderate to severe disease, which is reassuring.

What are the clinical symptoms of the new subvariables?

Fever, sore throat (often severe), nasal congestion, body aches, loss of taste, and mild cough are the predominant symptoms reported. Diarrhea is also occasionally reported, but appears to be less common than the frequency reported with earlier Omicron strains. For most individuals, symptoms appear to improve within four days, with fatigue and a mild cough lasting longer.

We are seeing many more cases of infection again in the current boom. Does this indicate that the immunity provided by the previous variants and vaccination is not sufficient protection?

Immunity can be defined as the body’s ability to contain an infection and not allow it to cause serious damage. If you use this definition, it appears that previous infections and vaccinations offer individuals a strong immunity to Covid-19. However, prior infection and/or vaccination may not always protect an individual from infection, as variants such as Omicron are known to be ‘escape variants’ that can avoid the first line of defense against infection.

Hospitalization rates are very low in the current wave. Does this show that new variants of Covid-19 are becoming more transmissible and less virulent?

Fortunately this appears to be the case. However, we must not ignore the role played by vaccination, and the “lower virulence” could be a combination of the virus being milder and the immune response much stronger. In high-risk people who are not immunized without prior exposure to the virus, even mild strains can cause severe disease, so we must strive to vaccinate everyone.

People who have been given boosters get infected again. International data also shows high penetration injuries. How powerful are the protections offered by current vaccines?

We need to constantly remind ourselves that vaccines are designed to create an immune response that prevents severe disease, and current vaccines and boosters seem to be doing an excellent job. We must reconsider the role of boosters among individuals, who have normal immune systems and do not have comorbidities, as frequent boosters in these individuals may not be necessary. Studies clearly show benefit among immunocompromised individuals, and all our future efforts should target this group.

What is the current trend of hospitalization in Mumbai?

It appears that a large proportion of hospital admissions are of individuals admitted with Covid-19, and not because of it. The primary respiratory manifestation of Covid-19 does not appear to warrant hospitalization in the majority. However, as with any other viral infection, individuals with underlying comorbidities display conditions associated with exacerbation of their comorbidities, leading to hospitalization. Despite this, the total number of individuals hospitalized appears to be a fraction of the peak seen last year.

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