This type of study is exactly what we need to assess the current state of broad quarantine measures in the US: combined serological testing and PCR testing for #SARSCoV2 #HCoV19 #COVID19 #coronavirus https://twitter.com/AdamJKucharski/status/1248188438098182145

This study of about 500 people from a heavily impacted town in Germany showed that 14% of those tested had IgG antibodies specific to #SARSCoV2, indicating that they had been previously infected. 2% were positive for viral RNA by PCR, indicating current (or very recent) infection

This suggests that even in areas with substantial transmission, the majority of people have not been infected and are likely to be susceptible to infection down the road. Easing stay-home orders could result in another wave of infections in the large proportion of naive people.

The good news is that there were many patients with detectable IgG levels, indicating that these people may be immune and could potentially go back to work. However, we don't know enough about protective immunity against #SARSCoV2 to be certain.

Based on what happens after *most* acute viral infections, IgG does indicate protective immunity; however, more studies need to be done to evaluate how well those antibodies can neutralize virus before we can say with more confidence that recovered COVID patients are safe.

Although this doesn't support total relaxation of stay-home policies, it does show that widespread virus and serology testing can help quantify risks, and allow us to apply more targeted containment measures. We need to do many more studies like this.

I disagree. Evidence so far shows that social distancing has been very effective at slowing spread, which saves lives. With widespread testing, targeted containment measures can be put in place that will allow relaxation of stay-home policies.