Epidemiological Tools that Predict Partial Herd Immunity to SARS Coronavirus 2

Yasuhiko Kamikubo; Atsushi Takahashi

Until March 9, 2020, the Japanese government did not restrict entry of tourists from areas of China outside Hubei Province which might have unintentionally allowed selective influx of S form to Japan. S type influx into Ireland and the Balkans may be due to travel restrictions in those countries restricted to infected individuals. In contrast to other areas in Japan, epidemic is ongoing in Nagoya City in Aichi prefecture and Sapporo City in Hokkaido, where the spread of the S form may have been incomplete as discussed above. In the United States of America and most European countries, travel from across China was restricted from the beginning of February, blocking the inflow of the S form from China. There is deep concern that serious outbreaks of SARS-CoV-2 in the United States and Europe may have been caused by the spread of the L form preceding the S form, by which up to 55% of the population may be infected as calculate above.