Why is the Delta variant of SARS-CoV-2 increasingly becoming a “variant of concern” in the current Covid-19 pandemic?

The Delta variant (B.1.617.2, formerly India variant) has become an increasingly prevalent strain of SARS-Cov-2 causing Covid-19 in many countries outside of India, including the United States and United Kingdom, particularly affecting younger unvaccinated persons.  Several features of the Delta variant are of particular concern. 1-7

  1. Delta virus appears to be more transmissible when compared to previously emerged variant viruses. Data from new Public Health England (PHE) research suggests that the Delta variant is associated with a 64% increased risk of household transmission compared with the Alpha variant (B.,1.1.7, UK variant) and 40% more transmissibility in outdoors. 1,8  
  2. Delta virus is also associated with a higher rate of severe disease, doubling the risk of hospitalization based on preliminary data from Scotland. In vitro, it replicates more efficiently than the Alpha variant with higher respiratory viral loads.5
  3. Delta virus may also be associated with reduced vaccine effectiveness with increased vaccine breakthroughs. One study found that Delta variant is 6.8-fold more resistant to neutralization by sera from Covid-19 convalescent and mRNA vaccinated individuals.5 Fortunately, a pre-print study released by PHE in May 2021 found that 2 doses of the Pfizer vaccine were still 88% effective against symptomatic infection with Delta variant  (vs 93% for the Alpha variant) and 96% effective against hospitalization; 1 dose was only 33% effective against symptomatic disease (vs 50% for the Alpha variant).  Two doses of Astra Zeneca vaccine were 60% effective against symptomatic disease from the Delta variant.8 
  4. Aside from its somewhat unique epidemiologic features, Covid-19 caused by Delta variant seems to be behaving differently (starting out as a “bad cold” or “off feeling”), with top symptoms of headache, followed by runny nose and sore throat with less frequent fever and cough; loss of sense of smell was not common at all based on reported data to date.1

What the Delta variant reminds us is, again, the importance of vaccination, masks and social distancing. The pandemic is still with us!

Bonus Pearl: Did you know that, on average, a Delta variant-infected person may transmit it to 6 other contacts (Ro~6.0) compared to 3 others (Ro~3) for the original SARS-CoV-2 strains found during the early part of the pandemic?1

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References

  1. https://www.bbc.com/news/health-57467051
  2. Knodell R. Health Advisory: Emergence of Delta variant of coronavirus causing Covid-19 in USA. Missouri Department of Health & Senior Services. 23 June, 2021. https://health.mo.gov/emergencies/ert/alertsadvisories/pdf/update62321.pdf
  3. Kupferschmidt K, Wadman M. Delta variant triggers new phase in the pandemic. Science 25 June 2021; 372:1375-76. https://science.sciencemag.org/content/sci/372/6549/1375.full.pdf
  4. Sheikh A, McMenamin J, Taylor B, et al. SARS-CoV-2 Delta VOC in Scotland: demographics, risk of hospital admission, and vaccine effectiveness. Lancet 2021; 397:2461-2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8201647/
  5. Mlcochova P, Kemp S, Dhar MS, et al. Sars-Cov-2 B.1.617.2 Delta variant emergence and vaccine breakthrough. In Review Nature portfolio, posted 22 June, 2021. https://www.researchsquare.com/article/rs-637724/v1
  6. Bernal JL, Andrews N, Gower C, et al. Effectiveness of Covid-19 vaccines against the B.1.617.2 variant. MedRxiv, posted May 24, 2021. https://www.medrxiv.org/content/10.1101/2021.05.22.21257658v1 vaccine efficacy
  7. Allen H, Vusirikala A, Flannagan J, et al. Increased household transmission of Covid-19 cases associatd with SARS-Cov-2 variant of concern B.1.617.2: a national case control study. Public Health England. 2021. https://khub.net/documents/135939561/405676950/Increased+Household+Transmission+of+COVID-19+Cases+-+national+case+study.pdf/7f7764fb-ecb0-da31-77b3-b1a8ef7be9aa  Accessed June 27, 2021.
  8. Callaway E. Delta coronavirus variant: scientists brace for impact. Nature. 22 June 2021. https://www.nature.com/articles/d41586-021-01696-3 

Disclosures: The listed questions and answers are solely the responsibility of the author and do not necessarily represent the official views of Mercy Hospital-St. Louis or its affiliate healthcare centers, Mass General Hospital, Harvard Medical School or its affiliated institutions. Although every effort has been made to provide accurate information, the author is far from being perfect. The reader is urged to verify the content of the material with other sources as deemed appropriate and exercise clinical judgment in the interpretation and application of the information provided herein. No responsibility for an adverse outcome or guarantees for a favorable clinical result is assumed by the author.

Why is the Delta variant of SARS-CoV-2 increasingly becoming a “variant of concern” in the current Covid-19 pandemic?

My patient with Covid-19 and abdominal pain has an elevated lipase. Is there a connection between Covid-19 and acute pancreatitis?

Acute pancreatitis as a complication of Covid-19 is infrequent.1 Despite reports of elevated amylase/lipase and/or acute pancreatitis in some patients with Covid-19,2 the exact role that SARS-CoV-2 plays in causing acute pancreatitis is unclear at this time.

A retrospective study of over 11,000 hospitalized patients with Covid-19 in the U.S. found a point prevalence of acute pancreatitis of only 0.27%,3 while another retrospective study of Covid-19 patients seen in Spanish emergency rooms reported acute pancreatitis in only 0.07% of cases.4 Of interest, in the latter study, Covid-19 was associated with lower frequency of acute pancreatitis. Further adding to the controversy on the causative role of Covid-19 is lack of an observed increase in the incidence of acute pancreatitis during Covid-19 pandemic. 1

An earlier study from China reported mild elevation (<3x upper limits of normal) of amylase and/or lipase in 17% of patients with Covid-19 pneumonia, none of whom had abdominal pain. 5

The temporal relationship between Covid-19 and acute pancreatitis has varied from abdominal symptoms at the onset of Covid-19 symptoms to days after diagnosis of Covid-19? 1

Despite these disparate findings, Covid-19 related acute pancreatitis or pancreatic injury is plausible. Pancreatic ductal, acinar and islet cells express ACE2, an important receptor for SARS-CoV-2.1 Infection in the GI tract (virus can easily be found in the stool) may potentially spread from the duodenal epithelium to the pancreatic duct and the pancreatic parenchyma itself. Immune-mediated inflammatory response or endotheliitis caused by SARS-CoV-2 may also potentially explain reports of pancreatic injury in Covid-19. 1,2

Bonus Pearl: Did you know that SARS-CoV-2 has been found in pancreatic tissue of some patients who succumbed to Covid-19 and has been shown to infect human pancreatic beta cells in-vitro.6  Perhaps we should be on the lookout for diabetes as a consequence of Covid-19 as well!

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 References

  1. De-Madaria E, Capurso G. Covid-19 and acute pancreatitis: examining the causality. Nature Reviews Gastroenterol Hepatol 2021;18: 3-4. https://www.nature.com/articles/s41575-020-00389-y
  2. Kandasamy S. An unusual presentation of Covid-19: acute pancreatitis. Ann Hepatobiliary Pancreat Surg 2020;24:539-41. https://synapse.koreamed.org/upload/SynapseXML/2110ahbps/pdf/AHBPS-24-539.pdf
  3. Inamdar S, Benias PC, Liu Y, et al. Prevalence, risk factors, and outcomes of hospitalized patients with coronavirus disease 2019 presenting as acute pancreatitis. Gastroenterol 2020;159:2226-28. https://www.gastrojournal.org/article/S0016-5085(20)35115-5/pdf
  4. Miro O, Llorens P, Jimenez S, et al. Frequency of five unusual presentations in patients with Covid-19: results of the UMC-19-S. Epidemiol Infect 2020;148:e189. https://pubmed.ncbi.nlm.nih.gov/32843127/
  5. Wang F, Wang H, Fan J, et al. Pancreatic injury patterns in patients with coronavirus disease 19 pneumonia. Gastroenterology 2020;159:367-70. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7118654/
  6. Wu C-T, Lidsky PV, Xiao Y, et al. SARS-CoV-2 infects human pancreatic beta cells and elicits beta cell impairment. Cell Metab 2021 May 18. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8130512/

 

Disclosures: The listed questions and answers are solely the responsibility of the author and do not necessarily represent the official views of Mercy Hospital-St. Louis or its affiliate healthcare centers, Mass General Hospital, Harvard Medical School or its affiliated institutions. Although every effort has been made to provide accurate information, the author is far from being perfect. The reader is urged to verify the content of the material with other sources as deemed appropriate and exercise clinical judgment in the interpretation and application of the information provided herein. No responsibility for an adverse outcome or guarantees for a favorable clinical result is assumed by the author. Thank you!

My patient with Covid-19 and abdominal pain has an elevated lipase. Is there a connection between Covid-19 and acute pancreatitis?