A lot of countries in South America had very strict rules. Double-mask requirements, mandatory vaccines, stay-at-home days. What they perhaps lacked in access to vaccines, they tried to make up with those stricter rules. They also made deals with China & Russia for their vaccines, in lieu of limited access to Pfizer etc.

A better term would be “developing nations” . The term " third world" refers to not being part of NATO (or not aligned to NATO), and is outdated. Also, there are various sorts of developing countries, richer, poorer, and some are war or conflict zones.

Each one in a different way.

• High level government employees got vaccines from richer countries
• Rich people got their names added to the high level employees list
• Social distancing and telling everybody “good luck”
• Third world situations tend to weed out immuno-compromised humans fairly efficiently. So long as the higher humans survive, command and control below management level typically has 2-3 backup employees ready to take the chair.

Source: My brain and the random memories that survived the memory hunger games.