The omicron stew is simmering with a variety of reports, none of which are particularly definitive.
- Severity of illness - It's almost like you can decide what you want to believe and then find a study that supports your view. If you want to visit South Africa, you'd be pleased to find predictions that omicron causes relatively mild disease. Alternatively, looking at the UK gives you the opposite view. Which is correct? It is likely they both are, serving to point out that multiple variables impact how severity of disease is determined. Population age and risk factor distribution, season of the year, vaccination rates, prior natural infection experience (and with which variant), testing frequency, individual risk behavior .... I could go on and on. We need a little more time to see how things will fare in the US.
- Vaccine efficacy - It is very clear that no current vaccines are particularly effective in preventing infection, but some are more likely to protect against severe illness and death. A recent letter in the New England Journal of Medicine is noteworthy. Investigators at Rockefeller University measured neutralizing antibody titers from 47 individuals previously vaccinated and/or infected and found significant immune escape in all. On a more positive note, they found that a third mRNA vaccine dose or infection followed by mRNA vaccination results in significantly better protection.
- Testing - Well, the biggest problem here is test availability. You may have heard that FDA reported that antigen tests are less sensitive for detection of omicron compared to other variants. Note that this statement is based on testing inactivated specimens and, as the FDA cautions, does not replace clinical studies to document true sensitivity and specificity. Antigen tests are known to be less sensitive than PCR testing anyway, and this FDA report is likely true though not quantified. Bottom line, a negative rapid antigen test doesn't mean an individual is not infected. Still, some testing is better than none right now.
- How long will the omicron surge last and when will it peak? Get out your crystal ball, or if you want to delve deeper look at the modeling report from the University of Texas COVID-19 consortium. I can't even begin to understand the mathematical formulas used, but it gives a number of outcomes depending on which set of initial assumptions one uses. Again, suffice to say we'll need to wait and see what really happens.
- The new CDC quarantine and isolation media release and interim guidance for ending isolation - Talk about confusion, here we are! Note that this is a media release, not an actual formal guidance. I understand and agree with the need to balance safety with trying to keep necessary infrastructure (e.g. healthcare, transportation, schools) available by decreasing staff outages due to exposure or infection, but know that this is a calculated risk. More pertinent to healthcare providers and pediatric settings in particular, I am unable to find any significant data that inform duration of infectivity of children infected with omicron. The guidelines are for use for the general public and do not specifically address precautions to be taken for patients in clinics or inpatient settings. Only my personal opinion, but I would not relax any precautions for pediatric healthcare settings and still follow the prior recommendations for quarantine and isolation for children coming to a healthcare setting. Note that CDC does have new guidance on contact tracing in schools.
- NPI - At least we still have nonpharmaceutical interventions that help, if we would only use them. If you can, use a NIOSH-approved N95 of KN95 mask.