Sep 24, 2020

Axios Science

By Alison Snyder
Alison Snyder

Thanks for reading Axios Science. This week we look at the role of viral load in COVID-19, vaccines for the disease, how pandemic shutdowns changed birdsong and more.

Today's newsletter is 1,805 words, a 7-minute read.

1 big thing: Viral load is a puzzle in COVID-19

Illustration: Eniola Odetunde/Axios

How sick a person gets from a virus can depend on how much of the pathogen that person was exposed to and how much virus is replicating in their body — questions that are still open for the novel coronavirus, Eileen and I write.

Why it matters: As people try to balance resuming parts of their daily lives with controlling their risk of COVID-19, understanding the role of viral load could help tailor public health measures and patient care.

Driving the news: An analysis of 5,000 genomic sequences of the coronavirus from patients found those infected with a now-dominant strain with a specific mutation "had higher loads of virus in their upper respiratory tracts, a potential factor in making the strain spread more effectively," the Washington Post reports.

  • The research underscores open questions about COVID-19: How does the amount of virus in someone affect transmission to others, and the severity of the disease?

How it works: Viral dose is how much virus someone is exposed to when they are infected. Viral load is the amount of virus produced in someone's body after they are infected.

  • A higher infectious dose of a virus and a higher viral load are linked to more severe disease from influenza, poxviruses and other viruses.

For SARS-CoV-2, the virus that causes COVID-19, "there's accumulating data on both sides of the equation," Monica Gandhi, a professor of medicine and an infectious disease doctor at UCSF, tells Axios.

  • In a study of hamsters, for example, those infected with a higher dose of SARS-CoV-2 had worse outcomes than those with smaller amounts, supporting an earlier study on hamsters checking if "masks" helped prevent transmission, she points out.
  • Outbreak investigations show that where there's universal masking of a population, the severity of disease goes down.
  • Some researchers suggest a decline in death rate and the rise in asymptomatic cases in the U.S. this summer — both coming at a time when mask-wearing became more common — indicate reducing the dose of the virus may reduce the severity of disease.

"It's very interesting that it seems like it's correlating with masking, this lower rate of severe illness," says Gandhi, adding that the hypothesis remains unproven but has some growing evidence behind it.

What's happening: Evidence is emerging about the link between viral load and how severe COVID-19 is for a patient.

  • In a study of more than 3,000 patients in three New York City hospitals, nearly 40% who tested positive for COVID-19 and had a high viral load died in the hospital.
  • But the risk of dying was lower — dropping to about 15% — for patients with a low viral load, Michael Satlin, an infectious disease specialist at Weill Cornell Medicine and NewYork-Presbyterian, and colleagues reported last week in the journal Cancer Cell.

Yes, but: Other studies have also found some people without symptoms can have viral loads similar to those with symptoms. And children, who tend to be spared severe COVID-19 complications, can carry as much or more of the virus in their upper respiratory tract.

  • "Viral load is a part of the picture, but it's not the full picture," infectious disease specialist Ravina Kullar told MedPage Today, adding that disease severity depends on a person's immune system.

What to watch: Knowing a patient's viral load could be helpful to providers in determining how therapies should be directed, says Satlin.

Read the full story.

Bonus: Catch up quick on COVID-19
Expand chart
Data: The COVID Tracking Project, state health departments; Map: Andrew Witherspoon, Sara Wise/Axios

More than 200,000 people in the U.S. have now died of COVID-19.

Cases rose in 22 states over the past week, and the U.S. is now averaging about 43,000 new cases per day, per Axios' Sam Baker and Andrew Witherspoon.

No COVID-19 vaccine trials have been started in children in the U.S., Carl Zimmer reports in the NYT. The dose and delivery of a vaccine can be different for children, and some researchers say that testing should begin now so a vaccine could be ready for the next school year.

What's happening: On Friday, the Centers for Disease Control and Prevention posted new guidance based on evidence that SARS-CoV-2 can spread via aerosols. On Monday, it was taken down, drawing criticism and concern about the agency's competency and politicization at a critical time in the pandemic, writes Axios' Caitlin Owens.

What to watch: Manaus, Brazil, may have reached herd immunity, according to a new preprint paper, at a cost of as much as 66% of the population being infected with the virus and a high death rate. The city may be a "sentinel" for the world if the disease is left unchecked, Antonio Regalado reports in MIT Tech Review.

2. Where potential coronavirus vaccines stand in the U.S.
Table: Axios Visuals

Four vaccines for the novel coronavirus are now in late-stage testing in people in the United States.

Driving the news: Johnson & Johnson announced yesterday it began a phase 3 clinical trial of its COVID-19 vaccine candidate.

Key details:

1. Johnson & Johnson vaccine (Ad.26.COV2.S):

  • How it works: A noninfectious adenovirus — a common cold virus — is used to deliver a gene from the novel coronavirus to human cells and produce copies of the SARS-CoV-2 protein, potentially priming immune cells to fight infection.
  • The vaccine is being tested as a single dose and can be stored refrigerated for at least three months, potentially alleviating some of the concerns about the logistics of distribution.
  • The U.S. government has advance purchased 100 million doses of the vaccine if it is approved, with the option to buy 200 million more.

2. Moderna vaccine (mRNA-1273):

  • How it works: Messenger RNA — genetic material carrying information about a viral protein — is delivered to cells that produce the protein, which the immune system is then trained to recognize.
  • RNA vaccines are a newer technology, favored for their potential speed in development, but none have been approved for humans — for any virus.
  • The vaccine is being given in two doses and is stored frozen.
  • Moderna has a deal to sell 100 million doses of its potential vaccine to the U.S. government, which can buy an additional 400 million doses.

3. Pfizer vaccine (BNT162b2):

  • How it works: This vaccine is also an mRNA vaccine being tested as two doses.
  • It currently requires storage at -70°C (-94°F). A company spokesperson says they've developed dry ice shippers to maintain that temperature for up to 10 days and they hope to have a formulation that will be stored at -2 to -8°C (28.4 to 46.4°F) by mid-2022.
  • Pfizer has an initial agreement with the U.S. government for 100 million doses if the vaccine is approved, with an option for 500 million more doses.

4. AstraZeneca/Oxford University vaccine (AZD1222):

  • How it works: Similar to the Johnson & Johnson vaccine, this candidate is a viral vector vaccine but uses a different adenovirus.
  • The vaccine's trial in the U.S. is currently paused after a "suspected adverse event" in a participant in a U.K. trial of the vaccine.
  • It is being given in two doses, and the company says it is studying its storage and distribution requirements. A spokesperson for AstraZeneca tells Axios they expect it will require refrigeration.
  • AstraZeneca's agreement with the U.S. government is "inclusive of the development, production and delivery of 300m [million] doses of the potential vaccine, which includes the Phase III clinical trial," they added.

What to watch: As the world awaits results from these trials, some researchers are calling for the studies to be modified to ensure they are testing if the vaccine protects against moderate and severe disease, as well as covering all people.

  • Amidst growing public skepticism and distrust of vaccines, the FDA is planning to tighten requirements for assessing a vaccine's safety and effectiveness, the Washington Post reported.
3. Gene editing plants and animals to fight climate change

Illustration: Eniola Odetunde/Axios

Editing the genes of plants and animals could help mitigate greenhouse gas emissions from agriculture and other sectors, according to a new report highlighting the possible uses of the technology, Axios' Bryan Walsh writes.

Why it matters: For too long, the potential of biotechnology to address climate change has taken a back seat to engineering, chemistry and energy. But new advances in gene editing could make farming more efficient and take carbon out of the atmosphere.

By the numbers: The Information Technology & Innovation Foundation, a think tank for science and technology policy, concludes in a recent report that gene-editing technologies like CRISPR could lead to a 50% improvement in agricultural productivity by 2050.

Context: The ITIF argues the federal government will need to reduce regulatory burdens on gene-edited products, increase investment in R&D, and provide incentives for the adoption of gene-edited technologies.

The bottom line: Agriculture is a major source of greenhouse gases, and tools like CRISPR — properly regulated — will likely need to play a part in creating more sustainable plants.

4. Worthy of your time

The race to redesign sugar (Nicola Twilley — New Yorker)

Wildfires’ toxic air leaves damage long after the smoke clears (Katheryn Houghton — Kaiser Health News)

The accidental tree killers (Stephanie Pain — Knowable)

What is math? (Dan Falk — Smithsonian Magazine)

5. Something wondrous

White-crowned sparrow. Photo: Education Images/Universal Images Group via Getty Images

When San Francisco hushed during coronavirus shutdowns earlier this year, a common songbird responded by changing its tune.

Why it matters: Earlier work found birds alter their songs to compensate for urban noise. This study suggests they are "adaptable enough to shift back if noise pollution is removed," says Ken Otter, an ornithologist at the University of Northern British Columbia who wasn't involved in the study.

  • Alleviating noise pollution — through the adoption of electric vehicles or urban planning — could affect breeding and "benefit wildlife that rely on acoustic communication," says Otter.

During pandemic shutdowns, the background noise in urban areas near San Francisco was on par with rural areas and with that of the city in the 1950s, Elizabeth Derryberry of the University of Tennessee, Knoxville and her colleagues report today in the journal Science.

  • That created "a proverbial silent spring" — and a rare opportunity to study the songbird's response to less noise pollution.

What they did: The researchers compared recordings of different dialects of male white-crowned sparrows, Zonotrichia leucophrys, in urban and rural areas near San Francisco from spring 2015 and 2016 with those from April and May 2020.

  • During the quiet period, the urban sparrows sang more softly and the distance the song traveled more than doubled.
  • They also began to sing lower notes, what females perceive as a more challenging song that therefore may increase the male's sex appeal.

Last note: The signal-to-noise ratio of the sparrow song also doubled, which means people could hear four times more birds and may explain why people reported bird songs being louder during the shutdown, the researchers write.

Alison Snyder