Infectious disease in the news: COVID and Polio

Withdrawal of COVID restrictions: what’s the story?

As of August, per CDC guidelines, just in time for the coming school year, official recommendations call for being reasonable and cautious but

  • no required 6 feet of distancing, 
  • no asymptomatic testing, 
  • no quarantining after exposure. 

New guidelines don’t differentiate based on vaccination status.

In general the guidelines acknowledge that

  • ventilated spaces and good hand hygiene are nice anytime, any place.  
  • Masking and distancing are smart for high risk people when community cases are high. 
  • Continued boosting, pre-exposure antibody shot, medication with infection are considerations that make more sense the higher risk you are.

Main points in detail

  1. For robust exposure/Close contact with a case — No quarantining is required after exposure, no contact tracing will be used in most settings. Do wear a mask for 10 days around others after a robust exposure when indoors in public and receive testing ≥5 days after exposure (or sooner, if they are symptomatic). Let your upcoming contacts know you are in a 10 or even 14 day window after an exposure if that’s the case.
  2. For respiratory/ infection symptoms — receive testing if symptomatic.
  3. If infected — isolate for ≥5 days. If all symptoms are improving and there is no fever, come off isolation after 5 days and mask in public until 10 days. Use antigen testing in the 6-10 day period to come off masking if you are improving: if you have 2 consecutive negative tests 48 hours apart, the CDC considers you off even the masking protocol.

Bottom line: Be aware, be courteous.  I think it’s best to tell people you will be seeing if you’ve had a recent robust exposure or you are just coming off infection if you are within a 2 week window.

Why the changes? Because you’re immune. It’s not a novel virus anymore. “High levels of immunity and availability of effective COVID-19 prevention and management tools have reduced the risk for medically significant illness and death.” But there are other things too. Main other thing: Omicron doesn’t go to the lungs. Let’s not forget that.

Came out of no where

It very interesting to remember the Omicron story. It appeared in Nov 2021 in Africa and took over the global scene. It was observed to be very infectious but caused a milder syndrome with less morbidity and mortality, which stayed true as it spread around the world. It was not a direct lineage of the previous variants. It was on a distinct tract from the other variants, diverging in mid 2020, it is thought. And we haven’t had evolution away from it since it’s appearance — just subvariants. Competing hypotheses on origin are being examined.

Covid Case Update

Daily cases nationally are just under 100,000. Local tallied cases still around 30 daily in the entire county. Remember the BA.5 variant worry? If we are going to be subject to the anticipation anxiety we should also follow through with the resolution relief. We did not experience a surge. In fact, cases are falling now. Immunity is high. Restrictions are being withdrawn. Just a little note to be active in pushing back against fear. Fearful is no way to live. I recommend instead: being aware, courteous, calm, up for a challenge.


What?: Per CDC: In June 2022, there was a serious polio case in New York. ‘Vaccine-derived poliovirus type 2 was detected in stool specimens from an unvaccinated immunocompetent young adult from Rockland County, New York, who was experiencing acute flaccid weakness.’

‘The patient initially experienced fever, neck stiffness, gastrointestinal symptoms, and limb weakness. The patient was hospitalized with possible acute flaccid myelitis.’

This report describes only the second identification of community transmission of poliovirus in the United States since 1979; the previous instance, in 2005, was a type 1 VDPV.

How?: This represents a transmission within the United States to the case patient who had not travelled internationally  originating with a person who received a type 2-containing oral polio vaccine (OPV) abroad. OPV gives an attenuated infection which can revert and can spread from the vaccinated person who remains asymptomatic. Unvaccinated status is the main risk for illness. Type 2 VDPV is an intentionally-made, weakened vaccine virus that has reverted to be able to cause illness. It appears to be spreading on its own now. Recent years changes in the OPV may have unintentionally given it ability to spread.

Other cases?: Certainly. Myelitis is a rare complication. To think that there was only one case and it had this complication would be almost certainly inaccurate. ‘Roughly 3 in 4 people infected with polio are asymptomatic. Even if there are symptoms, they usually resemble those of the flu.’ Cases would be easy to miss. The reason polio was detected in the patient was because it was a serious case. We don’t test for it generally.

Per CDC stats: ‘one in 1,900 poliovirus type 2 infections among unvaccinated persons is expected to result in paralysis.’ CDC doesn’t underestimate, so these types numbers are often the worst case scenarios.

Wastewater: Wastewater surveillance has spring boarded with COVID-19. It’s unclear exactly what current wastewater detection patterns mean because as far as I can tell there is not a lot of comparable historical data. It’s important to note, however, that this vaccine derived virus is being detected. ‘VDPV (Vaccine-derived Polioviruses) have been detected in wastewater in the patient’s county of residence and in neighboring Orange County up to 25 days before (from samples originally collected for SARS-CoV-2 wastewater monitoring) and 41 days after the patient’s symptom onset.’

VDPV shedding from persons who received oral polio is a phenomenon that has occurred for decades but is increasing with a shift in the oral polio vaccine in 2016.

The big difference here is the identification of a serious case as described above. Vaccination against polio can provide protection, and falling vaccination rates are part of the story, but not the whole story. The OPV and viral reversion and the change to the vaccine last decade are a part of this emerging situation as well.

Follow up: ‘As of August 10, 2022, no additional polio cases have been identified.’

Summary: The US uses killed, injected vaccine which provides immunity against polio. Vaccination with the live attenuated oral polio vaccine abroad also provides immunity but presents the risk of reverting and introducing polio disease. Only the unvaccinated population is at risk for disease occurrence.

In addition to reviewing your personal risk profiles and prevention approach I recommend again: being aware, courteous, calm, and up for a challenge. It provides a degree of protection, a boost for life in general.