"#COVID Testing.

If you get a negative…

False negatives at the beginning of infection are very common, thanks to the virus mutating. In a recent study, #antigen & #PCR tests only agreed 47-58% of the time. If they did agree, there was a 1-8 day delay between a PCR turning positive & an antigen test turning positive.

The higher we are in a wave, the more skeptical you should be of a negative result. There are 2 things you can do to help reduce false negatives

Swab throat & salvia. These are positive days before the nose.

Repeat testing. 2 tests within 48 hours catch 92% of #symptomatic cases & 39% of #asymptomatic cases. 3 tests 48 hours apart detected 94% of symptomatic & 57% of asymptomatic patients.

If you get a positive…
Positives are positives. You’re infectious.

The faintness of a line provides clues, though:

Very bold line= you’re very contagious.

Barely see the line= you’re at the beginning or the end of your infection window."

https://yourlocalepidemiologist.substack.com/p/riding-the-covid-19-waves-2023-style

1/n

https://academic.oup.com/ofid/advance-article/doi/10.1093/ofid/ofad240/7148518 “In this multi-center prospective test-negative case-control study in Japan, the effectiveness of both BA.1-containing and BA.4/BA.5-containing #bivalent COVID#19 #mRNA #vaccines against #symptomatic #infection during the BA.5-dominant period was high compared to no vaccination (65% and 76%) and moderate compared to #monovalent vaccines administered over half a year before (46% combined).”

#Symptomatic patients also infected a higher proportion of contacts than #asymptomatic ones (44.2% vs. 36.4%).

The authors speculate that 0-9y/os being more often unvaccinated & requiring more frequent interactions at home, was the reason why they were so infectious. #COVID19

The bivalent mRNA boosters from Pfizer-BioNTech and Moderna cut the infection risk from the predominant COVID-19 strain by nearly half according to early data published by the CDC.

The updated boosters were 48% effective against symptomatic infection with the XBB/XBB.1.5 variant in persons aged 18-49 years compared to fully vaccinated individuals (2-4 monovalent doses) with no bivalent booster dose. Protection was slightly reduced in older groups: 40% effective in adults ages 50 to 64 and 43% effective in adults 65 and older.

These preliminary results indicate the bivalent vaccines provide additional protection and that everyone should stay up to date with recommended COVID-19 vaccines.

https://www.nbcnews.com/health/health-news/updated-covid-boosters-cut-infection-risk-xbb15-subvariant-half-cdc-fi-rcna67313

Study: https://doi.org/10.15585/mmwr.mm7205e1

#COVID19 #SARSCoV2 #Vaccine #Vaccination #mRNA #Pfizer #BioNTech #Moderna #PublicHealth #Prevention #Infection #Effectiveness #CDC #Symptomatic #Booster