Various data points. This is an upper bound, more calculated for Santa Clara county. International comparisons to lockdown level and case count changes. Assum

Various data points. This is an upper bound, more calculated for Santa Clara county. International comparisons to lockdown level and case count changes. Assuming serial interval of 4 and > 10x non-detection rate on March 31 and 3x now gives you this. Knowing people were dying if the disease in early February implies very high lack of detection when SIP was in place. (Likely over 800 infections a day when Santa Clara activated SIP) Edit: More detailed explanation above.