Japan's Mpox Outbreak Was Connected with International Travel

The Lancet recently published a Correspondence that concluded the continuous reporting of new mpox cases in Japan suggests that ongoing local transmission of the sexually transmitted virus might be occurring.

The first imported mpox case in Japan was reported on July 25, 2022, and patients have been sporadically reported since then, mainly with a history of international travel or after having been in contact with travelers.

In Japan, 8 mpox cases were reported in 2022.

However, Japan's Ministry of Health, Labor, and Welfare Health reported the 169th mpox cases as of May 28, 2023.

Compared with many countries, Japan is more closely connected with other Asian countries. Most of its outbound travel volume is for south, southeast, and east Asian countries with relatively large populations.

Some of these countries have reported new mpox cases in 2023. with and without a travel history. 

For example, Korea's Centers for Disease Control and Prevention (CDC) announced in April 2023 that it would raise the crisis alert level from ‘Level 1' to ‘Level 2 caution’ following a mpox outbreak of about sixty cases.

However, from January 2023, most mpox cases in Japan did not have a travel history. 

Because of the scarcity of mpox vaccination campaigns in Asia (including Japan), these new infections raise a concern that the global mpox outbreak might be entering another phase, a resurgence formed by the spread in Asia, wrote Akira Endo, Sung-mok Jung, and Fuminari Miura on May 31, 2023.

Although mpox vaccine-induced immunity is not complete, vaccination continues to be one of the most important prevention measures, says the U.S. CDC.

As of June 7, 2023, Bavarian Nordic's JYNNEOS® (MVA-BN) vaccine remains available in most countries. In the U.S. and U.K., this mpox vaccine remains available for free. 

JYNNEOS is a 2-dose vaccine developed to protect against mpox and smallpox infections. People need to get both doses of the vaccine for the best protection against mpox. The second dose should be given 4 weeks after the first dose.

Since the global mpox outbreak began in May 2022, the U.S. CDC has reported 30,450 mpox cases and 42 related fatalities in the U.S. as of May 31, 2023.

However, the CDC warns there could be a resurgence of mpox cases as people gather for festivals and other events during the summer of 2023.