Explained: Two new vaccines, an oral pill against Covid-19, and how they work

India has authorized the molnupiravir pill to treat Covid-19 patients, and the Corbevax and Covovax vaccines. Indian express examines the science behind them and their performance.

Corbevax: protein subunit vaccine

THE VACCINE : Corbevax, made by Hyderabad-based Biological E, is a protein subunit vaccine, which means that instead of the whole virus, it uses fragments of it to trigger an immune response. In this case, the subunit vaccine contains harmless protein S. Once the immune system recognizes the protein, it produces antibodies to fight off a real infection when it occurs.

The antigenic parts of the virus were developed by the Texas Children’s Hospital Center for Vaccine Development and under license from BCM (Baylor College of Medicine) Ventures. Biological E plans to start production at 75 million doses per month and expects to reach more than 100 million doses per month from February.

EFFICIENCY: Biological E has completed Phase III trials on more than 3,000 subjects at 33 study sites across India. It states that neutralization of antibody titers against the Delta strain “indicates vaccine efficacy> 80% for the prevention of symptomatic infections based on published studies”.

She has also conducted phase III clinical trials with an active comparator to assess whether this vaccine is superior to Covishield. “In the pivotal phase III study conducted with an endpoint of immunogenic superiority, CORBEVAX demonstrated a superior immune response compared to the COVISHIELD vaccine when evaluated for the geometric mean titers (GMT) of neutralizing antibodies (nAb) against the Ancestral-Wuhan strain and the globally dominant Delta. variant, ”the company said.

Molnupiravir: oral antiviral medicine

DRUGS: Molnupiravir, developed in collaboration by US companies Ridgeback Biotherapeutics and Merck, initially to treat influenza, is an oral antiviral candidate reconverted to treat Covid patients. It has been approved for the treatment of adult patients with Covid-19 “who are at high risk of disease progression”. It works by introducing errors into the genetic code of the virus, which prevents replication. Molnupiravir is available as 200 mg tablets; the recommendation in India is 800 mg twice a day for 5 days.

It will be manufactured by 13 Indian drug makers: Dr Reddy’s, Natco, MSN, Hetero, Optimus, Aurobindo, Mylan, Cipla, Sun Pharma, Torrent, BDR, Stride and Emcure based in Pune. Sun Pharma has announced that it will likely be available within a week.

EFFICIENCY: The UK’s medicines regulator cleared molnupiravir on December 4 because it was found to be ‘safe and effective’. The United States (clearance Dec. 23) has not permitted its use for more than five consecutive days, or in patients under the age of 18, as it can affect bone and cartilage growth.

explained | What is Molnupiravir, the Covid-19 pill approved by India?

In India, the recommendation is to treat adult Covid patients with oxygen levels above 93%, who have a high risk of disease progression, and for the drug to be retailed only on prescription.

Covavax: recombinant nanoparticle vaccine

THE VACCINE : Covavax, manufactured by the Serum Institute of India (SII), is also a protein subunit vaccine, but uses recombinant nanoparticle technology. It was developed by the American company Novavax. Harmless copies of the spike protein are grown in insect cells; the protein is then extracted and assembled into virus-like nanoparticles. Novavax used an immune system stimulating compound (adjuvant). The same technology is used for HPV and hepatitis B vaccine.

On November 17, the Philippine FDA granted SII a license to market the vaccine in the country. On December 20, the WHO released an emergency use list for the vaccine.

EFFICIENCY: SII said the vaccine had been evaluated in two Phase 3 trials: a UK trial that demonstrated 96.4% efficacy against the original viral strain, 86.3% against Alpha and 89.7 % overall efficiency; and the PREVENT-19 trial in the United States and Mexico which demonstrated 100% protection against moderate and severe disease and an overall efficacy of 90.4%.

On December 2, Novavax announced that patients who received a third booster dose (6 months) of this vaccine produced “robust anti-Spike IgG responses” after a booster dose on day 189. “The neutralization titers were overall multiplied by 4.3 compared to the maximum response observed after the primary vaccination ”, he declared. The company said it would begin testing whether antibodies from previously vaccinated individuals can neutralize the Omicron variant, with lab data expected in the coming weeks.


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