Dr. Suhendro Sastrowiwoho was fully vaccinated and eager to help this month as Indonesia faced a new and deadly wave of Delta variant coronavirus cases. His daughter and son-in-law, both trained as doctors, told him to rest. He was 74 years old, they warned, and the virus was evolving in unexpected ways.

       On June 18, Dr. Suhendro died just days after testing positive for Covid-19. Like other frontline medical workers in his small town of Kudus, on the island of Java, he had received a double dose of Sinovac Biotech, the Chinese-made vaccine.

       “His love was taking care of his patients and helping people,” said Angeline Dewi Suhendro, his daughter, whose husband is now also hospitalized with Covid. “We forbade him to practice because Covid cases were shooting up, but he insisted.”

       While the West appears to be recovering from the worst of the coronavirus pandemic, some countries without access to plentiful vaccines are facing their most devastating outbreaks yet, as more contagious variants spread quickly. Other countries are discovering that certain vaccines may not be as effective as others in preventing infections caused by these variants.

       Indonesia, the world’s fourth most populous country, is facing both problems at the same time. On Thursday, the country recorded more than 20,000 cases of Covid-19, the highest number since the pandemic began. Oxygen is again running out at hospitals in the capital, Jakarta, and the national percentage of positive Covid tests reached 14.6 percent this past week. By comparison, the weekly positivity rate in the United States is now 1.8 percent, according to the Centers for Disease Control and Prevention.