Vaccine Manufacturers Practicing for Worse COVID-19 Variants to Emerge

Coronavirus variants concept

Winter is quickly approaching in the U.S., but a potential “escape variant” of SARS-CoV-2 has us bracing this year. Vaccine makers aren’t taking a wait-and-see approach but actively preparing for what may come next.  

In June, Pfizer CEO Albert Bourla promised his company could get a new COVID-19 vaccine ready within 100 days if needed. While current vaccines are highly effective against strains seen today, it’s possible that a new dominant strain could emerge soon that would be immune to the approved vaccines.  

Like a Broadway production months before the performance, Pfizer, Moderna, and AstraZeneca have been running “dress rehearsals” by adapting their current formulations to match present known SARS-CoV-2 variants. The teams have been modifying the vaccines to tackle Beta or Delta, running a clinical trial, and regrouping to smooth out the bumps.  

“At some point, inevitably, we’re going to have to make variant vaccines—if vaccines are the way population immunity will be maintained—but we’re not at the point where we can confidently predict the evolution of the virus,” says Dr. Paul Bieniasz, a virologist at the Rockefeller University in New York City. “Practicing with existing variants seems like a reasonable approach.” 

As to why they aren’t updating the current vaccines to fight the Delta variant, the predominant strain circulating the globe, the answer is a common one— time and resources. The current formulations are already FDA-approved and are manufactured at full speed. Any adjustments to the formula will have to be retested in human clinical trials, reapproved by the FDA, and then updated in manufacturing.  

Since practice makes perfect, Pfizer and partner BioNTech are already testing the Beta-specific RNA vaccine in a placebo-controlled trial as well as a multivalent vaccine trial targeting both Delta and Alpha variants. But there are no plans to stick the public with these formulations. 

“We’re not doing that because we actually think we need a new vaccine for those strains,” says Dr. Philip Dormitzer, vice-president and chief scientific officer of viral vaccines and mRNA at Pfizer, based in New York City. “We want to practice all aspects of executing a strain change—the preclinical research, the manufacturing, the clinical testing, and the regulatory submissions—so that if we do see a variant out there that truly escapes vaccine immunity, we’re ready to go fast.” 

Moderna has tests in the works to try new RNA vaccines against Beta, Delta, and a combination of the original strain with Beta. By submitting test cases to the FDA, the company hopes to establish the fastest route to approval. The Beta strain carries mutations, making it more resistant to vaccinated person’s antibodies fighting against it.  

The U.K. is seeing a surge in the Delta variant that may give the virus survival advantages. Calling it “Delta Plus,” the changes to the strain are subtle, but initial investigation believes it is likely to be up to 10 percent more transmissible.  

The mutated strain now accounts for 6% of U.K. COVID-19 cases. The U.K. has one of the highest COVID-19 infection rates in the world right now, reporting between 40,000 to 50,000 new cases per day. It isn’t yet clear if the Delta Plus strain is an underlying factor to these high numbers.  

Cambridge’s AstraZeneca has launched a study with over 2,800 participants to trial a Beta-specific viral-vector vaccine. “We’re definitely practicing with this one, but we are also developing it, and if it’s successful, we will have it ready to use,” says Mene Pangalos, executive vice-president of biopharmaceuticals research and development at AstraZeneca. 

Each year the flu vaccine is updated in its formulation to match whatever scientists believe the most common strain will be. The update to the vaccine doesn’t typically require clinical testing. The hope is that a similar process could be implemented for COVID-19 vaccines, where the formulation could be easily updated to match the emerging strain.  

Scientists believe that COVID-19 is here to stay and will soon move from pandemic to endemic, a manageable communicable disease that we learn to live with, like our annual run-ins with the flu season.  

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