DELTA VARIANT. The Delta variant (called before “Indian”) was responsible for a long time for all the positive tests screened in France, before being gradually replaced by Omicron, which became the majority in this 5th wave of Covid. Origin, symptoms, incubation, effectiveness of Pfizer or Moderna … Knowledge.
[Mis à jour le 5 janvier 2021 à 15h16] The Delta variant is one of the mutations of the original strain of Covid. He was first detected in India in October 2020 where he was responsible for a major epidemic wave. More contagious than the initial form of the virus, it has developed in many countries around the world like France, the United States, Australia, the United Kingdom or China. This variant is more transmissible than other Covid mutations (around 40 to 60% more transmissible than the Alpha variant, around 60% than the Beta and around 30% than the Gamma variant). This variant (L452R mutation) has long represented 100% of sequences that can be interpreted in France, according to Public health France. But since November, it is gradually replaced by the variant Omicron, more transmissible, which is now the majority. As of December 27, 62.4% of the screening tests indicated a profile compatible with Omicron. But Omicron would be 2 to 3 times less severe than Delta, estimates the government. “Delta threatens our resuscitations with its serious forms. Omicron threatens our medical beds with its many symptomatic forms. In both cases, the booster vaccine protects“, reminded Olivier Véran, Minister of Health on Twitter. “The danger is far from over, Gabriel Attal confirmed on January 5. If the Delta wave reaches a plateau in terms of contamination, it is still very strong in our hospitals, especially in parts of the South. ” What are the peculiarities of the Delta variant? His symptoms ? What is its contagion? His R0? Which dangers on the long term ? The vaccines reduce its transmission? Knowledge.
What is the origin of the Delta variant?
the Indian variant or “Delta” has been “first spotted October 5, 2020 near Nagpur“, a city in the center of
- B.1.617.1 (Kappa)
- B.617.2 (Delta, the most frequent in France): it is this sub-lineage which has been classified as “worrying” by the World Health Organization. “It became evident that more risk to the public is associated with B.1.617.2, while lower transmission rates have been observed with the other sublineages.”, specifies the WHO in its weekly epidemiological update on the pandemic.
- B.1.617.3
The Delta variant also presents a sub-variant : the AY.4.2, detected in 10% tests in England in October 2021. This sub-variant “seems to have a slightly increased growth rate compared to (the original strain of) Delta (…) possibly due to a modification of the virus (transmissibility or immune evasion) or to the epidemiological context“, indicates the site of the British government in a report from October 21, 2021. Based on these considerations and the high level of uncertainty, AY.4.2 was designated as new variant under surveillance: VUI-21OCT-01.
What are the symptoms of the Delta variant?
If the Delta variant appears to be more contagious than other strains, it would cause typical symptoms of Covid-19. The data collected as part of the study of the symptoms of the application Zoe Covid suggest that the Delta variant would look like “a bad cold” in young people “who have milder symptoms anyway “. Anyone who thinks they have symptoms suggestive of Covid should take a test and self-isolate while waiting for the results.
Top 10 Most Common Symptoms For Delta Variant:
- Headache
- Sore throat
- Runny nose
- Fever
- Cough (continued)
- Tired
- Chills
- Loss of appetite
- Muscle aches
- Change / Loss of taste
The efficacy of the Pfizer and AstraZeneca vaccines against symptomatic forms of the Delta variant is said to be 79%.
What is the R0 of the Delta variant?
The R0, in epidemiology, is defined as the average number of people that a contagious person can infect. The R0 level of the historical Sars-Cov-2 virus is estimated at 3, that of the Alpha variant at around 4.5 and that of the varying Delta to about 6.6 (in the absence of barrier measures including vaccination).
How contagious is the Delta variant?
The Delta variant was responsible for the fourth epidemic wave of Covid in France in July 2021. “Robust data confirms that the Delta variant exhibits a 60% increase in transmissibility compared to the Alpha variant, so far the most transmissible ” informed the Covid Scientific Council July 6. In its risk analysis of July 28, Santé Publique France indicates that the Delta variant is twice as transmissible as the historic Sars-CoV-2 virus, 60% more transmissible than the Beta variant and 30% more than the Gamma. Among the possible factors that may explain this increase in the transmissibility of Delta, several different data sources indicate a increased viral load in the nasopharynx in infected people. However, if it infects more people, current data does not show no longer duration of infectivity of the Delta variant compared to other viruses circulating (variants or non-variants).
Which vaccines are effective against the Delta variant?
In the event of a complete vaccination schedule, “the efficacy of the Pfizer and AstraZeneca vaccines against this variant remains high against the symptomatic forms, although it seems less than for VOC Alpha (she would be from 79%, editor’s note), and very high against severe forms of COVID-19 (94%, note) “inform Public Health France in July 2021 from UK data. In addition, according to an American study carried out on more than 4,000 health care center and hospital workers in six states, the efficacy of Pfizer and Moderna vaccines has reportedly declined in the United States since the delta variant became dominant there, from 91% to 66% efficiency, reports the Centers for Desease Control and Prevention (CDC) on Aug. 24. However, the US authorities believe that the benefits of vaccination outweigh the risks of becoming infected. “While these interim data suggest a moderate reduction in the effectiveness of Covid-19 vaccines in preventing infection, the fact that the reduction in infections remains at two-thirds underscores the continued importance and benefit of vaccination.“, underline the authors of this work.
What dangers for young people and children?
The Delta variant would not cause more severe forms of Covid-19 in children and adolescents.
The double mutation present on the Indian variant would increase its transmission capacity. However, according to data released on September 3, 2021 by Centers for Disease Prevention and Control (CDC), the Delta variant would not cause more severe forms of Covid-19 in children and adolescents. The researchers relied on data from several Covid patients hospitalized in the United States and compared the hospitalization rates of 0-17 year olds between two periods (March to mid-June and mid-June to the end of July when the variant Delta was the majority in the United States). The rate was certainly multiplied by 5 between the two periods, but the authors note that “the proportion of children and adolescents hospitalized for serious illness” was “similar” between March and the end of July. Of the 3,116 children hospitalized in three and a half months before the Delta variant, 26% were admitted to intensive care. After the Delta variant became the majority, out of 164 hospitalizations recorded in a month and a half, 23% of children went through intensive care.
Sources:
– Risk analysis on emerging variants of SARS-CoV-2 carried out jointly by Public Health France and the CNR for respiratory infection viruses Update 07/28/2021
– Stowe Julia AN, Gower Charlotte, Gallagher Eileen, Utsi Lara, Simmons Ruth, Thelwall Simon, Tessier Elise, Groves Natalie, Dabrera Gavin, Myers Richard, Campbell Colin, Amirthalingam Gayatri, Edmunds Matt, Zambon Maria, Brown Kevin, Hopkins Susan, Chand Meera, Ramsay Mary, Lopez Bernal Jamie Effectiveness of COVID-19 vaccines against hospital admission with the Delta (B.1.617.2) variant. Public Health England Publishing. 2021.
– Gisaid: database and monitoring network for variants