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Pfizer’s COVID-19 Treatment Shows In Vitro Efficacy Against Omicron
In other COVID news, Merck and UNICEF expand access to its COVID-19 treatment to low- and middle-income countries and Australia grants provisional registration for Novavax’s vaccine.
Pfizer recently announced that its COVID-19 treatment, Paxlovid, maintained plasma concentrations many-fold times higher than the amount required to prevent the Omicron variant from replicating in cells.
The first of the two in vitro studies tested Paxlovid against the Mpro enzyme from several SARS-CoV-2 variants of concern, including Omicron, in a biochemical assay. Results showed that the drug was a potential inhibitor of its target.
Additionally, researchers noted that Paxlovid showed its continued ability to prevent in vitro viral replication.
The second study tested Paxlovid against several variants in an antiviral, cell-based assay. Researchers tested reduction in viral load through polymerase chain reaction (PCR) analysis.
In the study, Paxlovid’sPaxlovid’s half- maximal effective concentration (EC50) was 16 nanomolar (nM) for the Omicron variant, compared to 38 nM for the USA-WA1/2020 variant. These results reaffirm the drug’s robust in vitro antiviral activity.
These study results align with those observed for other variants, including Alpha, Beta, Gamma, Delta, Lambda, and Mu.
“We specifically designed Paxlovid to retain its activity across coronaviruses, as well as current variants of concern with predominantly spike protein mutations,” Mikael Dolsten, MD, PhD, chief scientific officer and president of worldwide research, development, and medical at Pfizer, said in the announcement.
“Following the clinical findings – showing Paxlovid reduced risk of hospitalization or death by nearly 90% compared to placebo for high-risk patients when treated within five days of symptom onset – we are encouraged by these initial laboratory findings,” Dolsten continued.
The Icahn School of Medicine at Mount Sinai conducted an additional study, which leveraged SARS-CoV-2-specific immunofluorescence-based assay to detect the virus and measure the in vitro potency of Paxlovid.
Researchers observed half maximal inhibitory concentration (IC50) values ranging from 22 to 225 nM for Paxlovid, compared to USA-WA1/2020, where the IC50 was 38 to 207 nM.
These results are consistent with previous study findings.
Merck, UNICEF to Distribute 3M Courses of COVID-19 Treatment, Molnupiravir
Merck recently signed a long-term supply agreement with the United Nations Children’sChildren’s Fund (UNICEF) to facilitate broad global access for its COVID-19 treatment, molnupiravir, in low-and middle-income countries.
Under the agreement, Merck will allocate up to three million courses of molnupiravir to UNICEF throughout the first half of 2022.
Merck’sMerck’s supply and access approach includes producing millions of therapy courses and granting voluntary licenses to generic manufacturers and the Medicines Patent Pool to increase affordability and accessibility.
Additionally, the company continues to partner with governments and other organizations to boost quality-assured supply in the developing world.
“Merck is delivering on our commitment to make molnupiravir available – — widely, quickly and equitably. Through this groundbreaking agreement with UNICEF, millions of patients in more than 100 low- and middle-income countries will gain access to molnupiravir through UNICEF and the ACT Accelerator Therapeutics Partnership in the first half of 2022,” Robert M. Davis, chief executive officer and president of Merck, said in the announcement.
So far, molnupiravir was authorized in over ten10 countries, including the US, UK, and Japan.
Australia Grants Provisional Registration for Novavax’sNovavax’s COVID-19 Vaccine
Australia’sAustralia’s Therapeutic Goods Administration (TGA) recently granted approval for provisional registration of Novavax’sNovavax’s COVID-19 vaccine, NVX-CoV2373, for individuals 18 years and older.
TGA based its approval on the totality of preclinical, manufacturing, and clinical trial data, including two pivotal Phase 3 clinical trials.
The first trial, PREVENT-19, enrolled nearly 30,000 participants in the US and Mexico. And the second trial enrolled 15,000 participants in the UK. NVX-CoV2373 was highly effective with a reassuring safety and tolerability profile in both trials.
Serious adverse events were low and balanced between vaccine and placebo groups. In Australia, the vaccine will be found under the brand name Nuvaxovid.
“The grant of provisional registration of Nuvaxovid by the TGA reflects Novavax’Novavax' increasing momentum around the globe and represents the first- protein- based COVID-19 vaccine authorized for use in Australia,” Stanley C. Erck, president and CEO of Novavax, said in the announcement.
In January 2021, Novavax and the Commonwealth of Australia announced an advance purchase agreement for 51 million doses of NVX-CoV2373 with the option for an additional 10 million doses.
Novavax stated that it will continue to collect and analyze real-world data and monitor the safety and evaluation of variants as the vaccine is distributed.
