CME INDIA Presentation by Dr. S. K. Gupta, MBBS, MD (Med), CFM (France), Senior Consultant Physician, Max Hosp., Delhi.

Quick Take-Aways

  • Despite a low number of tests conducted, COVID-19 cases have spiked in March 2023, coinciding with an uptick in seasonal influenza H3N2 cases. India has reported a total of 6000 cases, with the XBB.1.16 lineage considered to be the cause of the surge.
  • Genomic surveillance data shows that XBB.1.16 accounts for over 30% of all sequenced genomes in March 2023, and its share of infections is increasing.
  • The XBB 1.16 subvariant is known to be a highly transmissible variant with a high infectivity rate. This subvariant has mutations on the amino acids and nucleotide space, which gives it the ability to escape hybrid immunity achieved by vaccination and previous exposure to the virus.
  • Although preliminary data suggest no difference in clinical severity between XBB.1.16 and other Omicron variants, there is a higher risk of reinfection due to its fast-growing ability. Therefore, it is crucial to monitor the spread of the XBB.1.16 lineage if COVID-19 cases continue to rise.
  • The signs and symptoms of the XBB.1.16 variant are very similar to those of the Omicron variant. These symptoms include a high-grade fever lasting over 48 hours, cough, sore throat, body pain, severe headache, cold, and abdominal discomfort. However, patients with XBB.1.16 have not shown any loss of smell or taste. Most of the patients with this variant have mild to moderate disease and are being managed on home isolation
New Covid Strain - XBB.1.16 - What Physicians Must Know?

Immune Escape Phenomenon

  • It is Omicron Variant similar to XBB.1.5 but with additional mutation in Spike protein It has limited Growth advantage. But initial trends suggest immune escape among Indians.
  • Despite three years into the pandemic there are no significant changes in the Covid 19 Management protocols released by ICMR.
  • But we are far more confident because of hybrid immunity (wide spread subclinical infections superimposed on excellent vaccination coverage by effective vaccines).

Co-morbid patients need attention

  • Patients with advanced comorbidities, old age people Morbidly obese immunocompromised people individuals, immunosuppressive therapy, systemic steroid therapy need to be careful.
  • Patients with Influenza-like illness (ILI) should be asked to wear mask.
  • Patients with ILI and comorbidities must be tested for Covid-19.
  • Young should isolate themselves from old people.

Vaccination does not guarantee Reinfection

  • IM Vaccination done so far does not guarantee against reinfection.
  • Even mild covid can lead to lingering symptoms called Long Covid.
  • Vaccination protects against Severe disease but not against infection.

Why Alarm Bell needed?

  • The way case numbers have doubled from~ 1300 on 23 March 23 to ~ 3100 on 31 March should not be viewed lightly. Doubling time of less than 5 days could be a sinister sign. The positivity rate has crossed 5% in several states.
  • Symptoms are no different from Flu.
  • So, the complacency of mistaking Covid as Flu can cost dear to society.

Recent Trends

  • In a short study from Maharashtra 11 people out of 42 had taken a precautionary dose. (25%) 10 required hospitalizations. Four (30%) of the hospitalized patients needed oxygen. These percentages are in line with the initial days of the Pandemic.
  • Though numbers are small in study but initially the percentages are guiding force.
  • Need to be extremely cautious and watchful.
  • Avoid unnecessary travel/events.

Suggestions

  • Urge the Govt to allow the 2nd Dose of Booster (in all the 4th dose of vaccine) to healthcare workers, front line workers, elderly people and people with comorbidities and immunocompromised individuals and gradually extend to other groups.
  • Watching virus behaviour for another two weeks might be a strategy but 4th dose vaccination may not be delayed rather advocated advised and augmented proactively.
  • iNCOVACC nasal vaccine could be an excellent vaccine in present scenario saving the nation.
  • Presently it is available on the Cowin App but only up to the 3rd dose.
  • Whatever be the scenario damage is likely to be lesser than the first two waves but it would be prudent to further minimise it.

CME INDIA Learning Edge

  • The SARS-CoV-2 virus has recently adopted a new strategy to evade T cells immunity. After successfully employing “convergent evolution” at the Spike protein, the virus is inducing more mutations in non-spike regions such as the N protein and ORF proteins.
  • This new strategy is aimed at evading T cells immunity, as these regions are less targeted by the immune system. By mutating these regions, the virus is able to evade recognition by T cells and continue to replicate and spread.
  • The changes in the non-spike regions of the SARS-CoV-2 virus are manifesting in the emergence of new sub-lineages such as XBB.1.16, XBB.1.9.1, CH.1.1.12, and other offsprings of XBB.1.5.
  • These newer sub-lineages are more efficiently blocking the communication between virus-infected cells and T cells, which are a crucial component of the immune system’s response to viral infections.
  • By blocking this communication, the virus is able to evade the immune system and continue to replicate and spread. This poses a significant challenge to public health authorities and underscores the need for continued vigilance and research to understand and combat the evolving threat of SARS-CoV-2.
  • If the SARS-CoV-2 virus is successful in evading T cell immunity and persisting longer in the body, it could potentially lead to persistent inflammation, higher incidence of long COVID, and even autoimmune disorders in some individuals. It’s important to continue monitoring the evolution of the virus and to develop strategies to prevent or manage the potential health consequences associated with new variants.
  • This warrants continued research into effective treatments and vaccines, as well as continued public health measures such as testing, contact tracing, and social distancing to help prevent the spread of the virus.

CME INDIA Tail Piece

  • On March 29, Maria Van Kerkhove, PhD, the WHO’s technical lead for COVID-19, has stated that the strain has similarities to XBB.1.5, which is currently the dominant strain in the United States.
  • The new strain, XBB.1.16, has an additional mutation in the spike protein, which has been shown to increase infectivity and potential pathogenicity in laboratory studies.Most of the new COVID cases in India is supposed to be due to XBB.1.16.
  • The World Health Organization is monitoring more than 600 omicron subvariants, XBB.1.16  is potentially becoming more transmissible and severe.
  • To date, there have been approximately 800 sequences of XBB.1.16 from 22 countries, with most of the cases reported in India.
  • According to Van Kerkhove, laboratory studies have indicated that XBB.1.16 has demonstrated increased infectivity and potentially increased pathogenicity. She emphasized that XBB.1.16 is a variant to monitor closely, as it has been circulating for a few months.
  • XBB.1.16 now has a relative growth advantage of 166.33% (CI: 128.3-204.6)
  • While there have not been any observed changes in severity in individuals or populations, the surveillance systems are in place to detect any such changes

References:

  1. https://who.canto.global/s/G2PIS?viewIndex=0&column=video&id=4tt7vem1qh3kd4drk88f6b2e1k
  2. https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1141754/variant-technical-briefing-51-10-march-2023.pdf
  3. https://www.who.int/news/item/18-03-2023-sago-statement-on-newly-released-sars-cov-2-metagenomics-data-from-china-cdc-on-gisaidl


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