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Peter Attia MD#117 – Stanley Perlman, M.D., Ph.D.: Insights from a coronavirus expert on COVID-19
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CHAPTERS
- 0:11 – 9:12
Guest Introduction and Path into Medicine and Virology
Peter Attia introduces Stanley Perlman and the episode's scope. Perlman describes his PhD training, his accelerated medical school, and his pediatric interest in how viruses affect the developing brain.
- •Perlman has studied coronaviruses for nearly four decades
- •Attia recommends listening after his episode with David Watkins
- •Perlman did a PhD before medical school, which he completed through a truncated program
- •He was drawn to how viruses interact with babies' brains
- •Coronaviruses in mice offered a model for demyelination similar to multiple sclerosis
- 9:12 – 17:55
What Is a Coronavirus? Genome Size, Naming, and Viral Roles
Perlman explains how viruses are grouped into a family and what is unusual about coronaviruses, such as their large RNA genome. The discussion also covers whether viruses serve useful roles and where the name comes from.
- •Viruses are grouped by appearance, replication strategy and genetics
- •Coronavirus genomes are about four times the size of poliovirus's and code for around 25 proteins
- •Nearly all of a virus's genome codes for proteins, unlike the human genome
- •Viruses in oceans and the gut may play beneficial roles
- •The name comes from surface projections resembling a crown or the sun's corona
- 17:55 – 25:37
Animal Hosts, Species Jumping, R_0, and Herd Immunity Basics
The conversation turns to whether human viruses usually have animal hosts and how that affects elimination. It also touches on measles, polio, West Nile, HIV origins and the late-1990s knowledge of common cold coronaviruses.
- •Measles and smallpox infect only people, which is why elimination is possible
- •Coronaviruses often cross species, and MERS is essentially a camel virus
- •A virus that adapts to humans may no longer infect its original animal host
- •Only two human coronaviruses (229E and OC43) were known before SARS
- •Common cold coronavirus immunity wanes and reinfection occurs
- 25:37 – 28:44
Perlman's Research Focus on Brain Infection and Immune Damage
Perlman describes why he stayed with coronaviruses in the 1990s: using a mouse virus to study how the brain clears a virus while tissue is destroyed. He explains this was tied to multiple sclerosis, demyelination and remyelination.
- •The mouse virus was used to study multiple sclerosis-like disease
- •He asked why clearing virus from the brain involves tissue destruction
- •Perlman started doing immunology in the 1990s
- •By the mid-'90s he was more focused on the disease-mechanism question than on prenatal infection
- 28:44 – 33:58
The 2002–2003 SARS Outbreak and Its R_0
Perlman recounts how SARS emerged from a live animal market in Guangzhou and spread globally through a physician in a Hong Kong hotel. They discuss R_0 values and why hospital spread inflated them.
- •SARS was almost certainly a bat virus that spread to other animals at a live animal market
- •Up to a third of market handlers had antibodies
- •One physician staying in a Hong Kong hotel seeded global spread
- •The R_0 of two to three hid much higher spread in hospital procedures
- •Measles has an R_0 around 15, while common cold coronaviruses are one to two
- 33:58 – 45:04
MERS and Why SARS and MERS Were Contained
The discussion covers the MERS coronavirus, its camel origin, its roughly 35% reported mortality, and the mystery of why it occurs only in the Arabian Peninsula. Perlman and Attia explain why both SARS and MERS failed to become pandemics.
- •Case fatality rates can mislead when milder infections go uncounted
- •MERS is a distant relative of SARS but shows some cross-reactivity
- •MERS cases continue in Saudi Arabia, though camels are infected in Africa without human cases
- •Human-to-human MERS spread occurs mainly in hospitals, with an R_0 near 0.3 outside them
- •SARS ended due to no animal reservoir and easy isolation of symptomatic patients
- 45:04 – 53:40
Why SARS-CoV-2 Is More Dangerous: Transmissibility, Receptors, and Mortality
Perlman and Attia consider how bat coronaviruses raised concern and why SARS-CoV-2 combines features of a cold virus and a lung virus. They compare lung pathology and fatality rates with SARS and MERS.
- •Surveys of bat coronaviruses found viruses that could enter human cells
- •SARS-CoV-2 behaves like a common cold virus in transmission and causes severe lung disease in some
- •Severe disease involves lots of virus plus an inappropriate immune response
- •SARS and the NL63 cold virus use ACE2 but differ in upper airway involvement
- •Perlman argues SARS-CoV-2's large pool of mild cases lowers its apparent fatality rate compared with SARS and MERS
- 53:40 – 57:01
Long-Term Effects in Survivors
Attia asks about lasting damage in people who recover from severe COVID-19. Perlman discusses the limited follow-up on SARS and MERS, possible fibrosis, neurological symptoms and immune-mediated mechanisms.
- •Perlman could not get follow-up information on MERS patients
- •Recovery may be slower for older people with comorbidities
- •Neurological problems in SARS were attributed to ventilators and steroids, with the virus only occasionally found in the brain
- •Immune-mediated effects such as those in Kawasaki-like disease in children are plausible
- 57:01 – 1:07:55
Early Pandemic Recognition and Preparing for the Next One
Perlman recalls when he realized COVID-19 was a big deal and why earlier outbreaks stayed confined. They discuss how hard it is to prepare for a pandemic that does not exist, and Attia argues for no-regret investments.
- •Perlman sensed in December from talking to Chinese colleagues that this was a big deal
- •Earlier outbreaks stayed geographically confined, and H5N1 never became transmissible
- •Funding for a disease that has disappeared is hard to justify in the grant system
- •Attia proposes stockpiling PPE, test reagents, contact tracing infrastructure and immune-modulating drugs
- •Perlman says testing targets were quick to identify but scaling up testing was the difficulty
- 1:07:55 – 1:13:24
Seasonality, Waning Immunity, and Herd Immunity
The discussion covers why common cold coronaviruses are seasonal and why people get reinfected. Perlman explains herd immunity and its relation to R_0, with a 60 to 70% threshold for SARS-CoV-2.
- •Cold coronaviruses are mostly winter and early spring viruses, for reasons not understood
- •Antibody responses to cold coronaviruses wane within a year or two
- •Smallpox antibodies were measurable decades later, in contrast
- •Herd immunity thresholds are about 95% for measles and 60 to 70% for most common viruses
- •Many asymptomatic infections do not change the threshold, only how many are already immune
- 1:13:24 – 1:22:32
Genetic Drift and the Cross-Reactive T Cell Question
Perlman says there is so far no evidence that SARS-CoV-2 drifts in a way that would defeat vaccines or prior immunity. They then discuss the Sette T cell study and Perlman's caveats about measuring activation rather than function.
- •OC43 varies, but other coronaviruses show little drift that affects immunity
- •No evidence that SARS-CoV-2 changes in ways that would undermine vaccines
- •Mild infections do not produce great immunity
- •Perlman is cautious about T cell cross-reactivity because the assays measure activation, not function
- •Target sequences show little homology with common cold coronaviruses
- 1:22:32 – 1:33:05
MMR, BCG, and Timing of Immune Therapies
They assess claims that MMR or BCG vaccination protects against COVID-19, which Perlman finds unsupported. The conversation moves to staging treatment: antivirals early, immune modulators later, and the need for biomarkers.
- •Perlman notes people over 50 had the real measles, mumps and rubella infections and sees no reason for cross-protection
- •Attia is skeptical BCG could provide the necessary specificity
- •Immune activation might help only if given just before or at exposure, and may harm once infection is established
- •Treatment may need to be staged by disease phase
- •Biomarkers and machine learning might identify who will progress
- 1:33:05 – 1:34:45
Alternative Origin Hypothesis
Attia asks about a paper arguing the virus may have circulated in humans longer than assumed and may not have come from the wet market. Perlman had not seen it but agrees the virus is remarkably well adapted to humans.
- •The paper argues for mostly person-to-person spread and genetic stability
- •Perlman had not read the paper
- •He agrees the virus is remarkably fit for humans
- •Attia plans to forward the paper to him
- 1:34:45 – 1:43:55
Durability of Immunity, Vaccines, and Closing Thoughts
Attia and Perlman discuss how to measure durable immunity and why preventing shedding matters more for society than protecting individuals from pneumonia. They discuss vaccine risk trade-offs and a human volunteer study design, then close with Perlman's outlook.
- •Perlman expects waning immunity after mild disease
- •Preventing transmission, not just severe pneumonia, is the key societal question
- •Attia argues vaccine risks require cost-benefit thinking
- •A reinfection study with cold coronaviruses could show whether shedding is reduced
- •Perlman expects antivirals and vaccines but is unsure how long they will work
