COVID-19 Update: Asymptomatic Infections, Antibodies in CSF

Ellie Kincaid

June 08, 2020

Editor's note: Find the latest COVID-19 news and guidance in Medscape's Coronavirus Resource Center.

Here are the coronavirus stories Medscape's editors around the globe think you need to know about today: 

Asymptomatic Infections 

Transmission of SARS-CoV-2 from people who are infected but asymptomatic appears "very rare," a World Health Organization (WHO) official said in a press briefing earlier today. From the data emerging from contact tracing studies so far, "it still appears to be rare that an asymptomatic individual actually transmits [SARS-CoV-2] onward to a secondary individual," said Maria Van Kerkhove, PhD, the WHO's COVID-19 technical lead. In a later tweet, she emphasized the importance of differentiating between individuals who are "truly asymptomatic" as opposed to presymptomatic or those with mild symptoms. 

Researchers came to a different conclusion after reviewing the asymptomatic infection rate from 16 diverse cohorts consisting of residents of cities, healthcare workers, residents of a nursing home, inmates in correctional facilities, and others. The prevalence of asymptomatic cases of COVID-19 may be "a significant factor" in the spread of SARS-CoV-2, they concluded. 

"The likelihood that approximately 40%-45% of those infected with SARS-CoV-2 will remain asymptomatic," they wrote, "suggests that the virus might have greater potential than previously estimated to spread silently and deeply through human populations."

Antibodies in CSF

Researchers found evidence of SARS-CoV-2 antibodies in the cerebrospinal fluid (CSF) of three patients with severe, laboratory-confirmed COVID-19 and encephalitis, according to a case series report. "We were able to show IgM, the acute phase reactant against COVID, in the spinal fluid of these patients, which is a direct indicator they had COVID in their brain," said lead author Karima Benameur, MD, a neurologist at Emory University School of Medicine in Atlanta, Georgia. 

PCR tests for SARS-CoV-2 RNA in the patients' CSF did not detect the virus' genetic material, but "just because the PCR in CSF is negative, this does not mean that the virus has not made it into the brain," Benameur said. 

Vaccine Rates Drop for All Ages 

Adults as well as children have gotten vaccinated at lower rates as routine care has been put on hold during the COVID-19 pandemic, according to an analysis from VaxCare, a vaccine program management company. The authors of the analysis point out that the vaccination drop is severe across all age groups, and although numbers have been improving as medical offices begin to reopen for primary care visits, the deficits are deep.

The data represent more than 240,000 doses of noninfluenza vaccines administered across 1146 ambulatory care offices, including 231 health departments, and the report compares noninfluenza vaccination rates from March 3 to May 11, 2019, to rates during the same period this year.

COVID-19 Overwhelms Border ICUs

Even as most California hospitals have avoided an incapacitating surge in coronavirus patients, some facilities near the Mexican border have been overwhelmed, Kaiser Health News reports. A reporter visited the intensive care units at two hospitals and documented the efforts to keep patients alive. 

Viral Shedding and Superspreading Events

Two HIV fellows who collaborate on a periodic deep dive into the COVID-19 literature summed up for Medscape the evidence thus far about the role of viral shedding and superspreading events in the transmission of SARS-CoV-2. 

"The growing understanding about the limited duration of infectiousness and the importance of superspreading events provides some much-needed good news for control of the pandemic," they write. 

Are Patients Dying "From" COVID or "With" COVID?

SARS-CoV-2 can kill by direct viral tissue destruction, disseminated intravascular coagulation, and frequently strange "immune" responses, pathologist and former editor-in-chief of Medscape George Lundberg, MD, writes in Medscape. But questions remain about COVID-19 and risk factors for death. Lundberg predicts that reports from many well-performed autopsies "will go a long way toward helping us to understand the pathophysiology of this disease."

In Memoriam

As frontline healthcare workers care for patients with COVID-19, they commit themselves to difficult, draining work and also put themselves at risk of infection. More than 1000 throughout the world have died. 

Medscape has published a memorial list to commemorate them. We will continue updating this list as, sadly, needed. Please help us ensure this list is complete by submitting names with an age, profession or specialty, and location through this form

If you would like to share any other experiences, stories, or concerns related to the pandemic, please join the conversation here.

Ellie Kincaid is Medscape's associate managing editor. She has previously written about healthcare for Forbes, the Wall Street Journal, and Nature Medicine.

For more news, follow Medscape on Facebook, Twitter, Instagram, and YouTube, and follow Ellie Kincaid on Twitter @ellie_kincaid.

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