The CDC has issued new travel advisories, including Hong Kong, New Zealand, Thailand, and Vietnam on its high-risk list.

The U.S. Centers for Disease Control and Prevention has expanded its list of "Level 4" travel warnings, now including more high-risk locations for COVID-19.

Recently, Vietnam was placed on the Level 4 risk list, just ahead of its reopening to international visitors on March 15.

Today, the CDC added three more places to its warnings: New Zealand, Thailand, and Hong Kong. Notably, mainland China still has a "Level 1: Low level of COVID-19" rating, despite the situation in Hong Kong.

This warning from the CDC follows New Zealand's announcement to lift self-isolation for travelers and initiate a plan to welcome visitors from "visa waiver" nations, including the U.S. and Canada, starting in July.

The CDC's Level 4 designation advises: "Refrain from traveling to these locations. If travel is necessary, ensure you are fully vaccinated beforehand."

As stated on the official CDC website, countries are assigned a Level 4 status when they report over 500 new COVID-19 cases per 100,000 people in the last 28 days.

The CDC's travel advisory system consists of four levels, starting from "low" risk and advancing to "moderate," "high," and the top tier, "very high." These ratings help guide Americans in their travel decisions during the ongoing pandemic as case rates fluctuate globally. The agency urges all travelers to be fully vaccinated before heading to any destination.

With the latest updates, the Level 4 warning list now encompasses 135 locations, representing over half of the world's countries and exceeding the total in all other CDC categories combined.

The Level 4 list has significantly increased in recent months, driven by the rise of the omicron variant—only 80 nations were classified as Level 4 in early January.

The CDC refreshes its warning lists every Monday.