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COVID-19 Vax Moving at Brisk Clip, but Will It Be Soon Enough?

BOSTON — Development of a COVID-19 vaccine is moving rapidly, according to the director of the National Institute of Allergy and Infectious Diseases (NIAID).

In a recorded message shown during a special session at the virtual Conference on Retroviruses and Opportunistic Infections (CROI), Anthony Fauci, MD, said the time from sequencing of the virus — which arose in central China in late December 2019 — to human trials of a vaccine candidate is expected to move with unprecedented speed — around 2 months.

In comparison, Fauci noted that the development time for a candidate vaccine for the SARS outbreak in 2003 was 20 months, while it took 11 months to develop a vaccine candidate for the H5N1 influenza outbreak in 2006, 4 months for a vaccine candidate for the 2009 H1N1 influenza, and 3.5 months for the Zika virus vaccine in 2016.

He said the COVID-19 vaccine that is furthest along is a collaborative effort by the NIAID Vaccine Research Center, Moderna Therapeutics, and the Coalition for Epidemic Preparedness Innovations. It is an mRNA vaccine candidate expressing the viral spike protein of COVID-19, Fauci explained.

Other potential COVID-19 vaccines in the works are a chimpanzee adenovirus-vectored candidate (NIAID Rocky Mountain Laboratories and Oxford University in England); a SARS recombinant protein candidate being evaluated for cross-neutralization (Baylor College of Medicine in Houston); and additional concepts such as recombinant spike vaccines, as well as other nucleic acid vaccine platforms, he said.

However, other methods of controlling the outbreak have been less successful, stated Ralph Baric, PhD, of the University of North Carolina Gillings School of Global Public Health in Chapel Hill, in a live broadcast CROI presentation.

In contrast to the 2003 SARS epidemic, Baric said that with the current epidemic of COVID-19 (or SARS2), “we don’t know what the animal reservoirs are so we can’t cull the animals that are transmitting to humans.” He added that “although hospitals still remain epicenters of disease expansion, barrier nursing hasn’t proved as effective as we like since there are about 1,700 healthcare workers affected in China.” Also, community spread by asymptomatic carriers is common with SARS2, “so this confounds quarantine and contract tracing,” he said.

“So it is going to be very difficult to control this SARS2 outbreak,” Baric said, adding that the pathogen appears to have multiple strains, which may make developing an effective vaccine to cover the spectrum of SARS2-like pathogens even more difficult.

Baric suggested that therapeutics may be a better route. “There are no approved drugs, immune therapeutics, and vaccines against group 2b coronavirus,” he noted. But drugs such as a remdesivir-ribonucleoside inhibitor might have value in COVID-19, as could the combination of lopinavir/ritonavir and interferon-beta. Therapeutic antibodies are also a possibility, Baric said, as is an investigational agent (GS-5734).

In another virtual CROI presentation, Zunyou Wu, MD, of the Chinese Center for Disease Control and Prevention, said the “lockdown” across China appears to have been effective as cases are now waning in that country.

Wu said that 80% of the patients who are infected with COVID-19 have mild disease at diagnosis, while 15% may develop severe disease, and 5% may become critical. About 10%-15% of mild cases progress to severe, and 14%-20% of those cases become critical, he stated.

Wu shared some key insights on COVID-19 from China:

  • The majority of cases arise from close contact of symptomatic cases
  • Transmission is driven by family clusters
  • Second-degree household attack rates were around 10% early in the outbreak, but fell to 3% with faster isolation
  • Virus shedding is highest early in the disease course and can occur 24-48 hours before symptom onset
  • Virus shedding usually continues for 7-12 days in mild/moderate cases and for >2 weeks in severe cases

Finally, Wu noted that truly asymptomatic infection is not known without serology, but appears to be rare (<1%) based on molecular testing. Ultimately, an estimated 75% of asymptomatic cases at time of diagnosis progress to full-blown disease, he said.

Last Updated March 10, 2020


Fauci, Baric, and Wu disclosed no relevant relationships with industry.