ATLANTA — Federal health officials will require temperature checks for the first time at five major American airports for people arriving from the three West African countries hardest hit by the deadly Ebola virus. However, health experts said the measures were more likely to calm a worried public than to prevent many people with Ebola from entering the country.

Still, they constitute the first large-scale attempt to improve security at American ports of entry since the virus arrived on American soil last month.

They are also a notable policy shift at a time of rising concern about the disease. Public health officials had initially resisted the move, saying such checks would be an unnecessary use of thinly stretched resources. But pressure for tougher action mounted. Republicans sharply criticized President Obama for what they called a lax response. Many, including Senator Ted Cruz of Texas, have suggested looking at air travel restrictions from West Africa, something the administration has rejected.

The temperature check requirements were announced hours after the first Ebola patient to have the illness diagnosed in the United States, Thomas Eric Duncan, a Liberian, died in a Dallas hospital, intensifying questions about whether he might have survived had he been admitted to a hospital when he first sought care there in late September.