LOS ANGELES (MarketWatch) — Is the U.S. Ebola screening effort really just a public-relations ploy?

Health officials say beefed-up defenses in five U.S. airports mean they will screen 94% of passengers flying in from Ebola-hit countries. But a check of airlines schedules shows that even if that figure is correct, a significant number of flights will bypass that extra security.

Dr. Joseph McCormick, professor at the University of Texas School of Public Health and former CDC official specializing in viral diseases, says the efforts seem to be the result of public pressure.

“I think that the screening program is, to some degree, a response to the media,” said McCormick, who once led a team investigating a 1979 Ebola outbreak in the Sudan.

At certain airports, it appears more than 6% of flights from the worst-hit West African countries — Guinea, Sierra Leone and Liberia — will bypass the extra screening process. These include Houston’s George Bush Intercontinental, Boston’s Logan Airport, Philadelphia International and Detroit’s Wayne County airport.

But the list also includes Dallas-Fort Worth, where Thomas Eric Duncan ended up on his way from Liberia. Duncan was diagnosed with Ebola in Dallas late last month and died earlier this week. As of now, he is the only patient to have been diagnosed with the virus in the U.S.

Reports say that Duncan’s itinerary took him through Washington-Dulles airport where one of the Ebola checkpoints is being set up, but most flights going to Dallas don’t make that stop.

Professor Lawrence Gostin of Georgetown Law School, a specialist in global health law, said that a course of action that excludes 6% of passengers poses a problem.

“If anyone thinks this is going to be foolproof, they’re wrong,” he said.

When Duncan died on Wednesday, the Centers for Disease Control and Prevention, along with the Department of Homeland Security’s U.S. Customs and Border Protection office, announced plans to beef up screening at four other international airports in addition to Dulles: Newark, Atlanta, Chicago-O’Hare and JFK in New York. The procedure involves taking the temperature of incoming passengers and having quarantine facilities at the ready.

By casting a net over those five airports, the agencies reasoned, they would be able to screen 94 out of every 100 passengers coming into the U.S. from the afflicted nations. That, coupled with efforts by West African nations, should be able to weed out virtually all potential Ebola threats, they say.

Federal officials insist they will be able to diligently watch for signs of those displaying symptoms of Ebola, regardless of whether an airport has the beefed-up security.

“[Customs] and the [Centers for Disease Control] have closely coordinated to develop policies, procedures, and protocols to identify travelers that are known by U.S. public health officials to have a communicable disease, and to handle in a manner that minimizes risk to the public that will continue being administered at all ports of entry,” Customs and Border Protection officials said in a prepared statement.

To get a sense of the screening coverage, MarketWatch took at look at relevant flights for sale through Web travel brokers. The airports in West Africa have only a handful of flights a day leaving the airports there, but there are dozens of options for getting into the U.S. through connecting flights in Europe, Asia and larger cities in Africa. Here’s what we found:

• From Roberts International airport in Monrovia, Liberia — the airport Duncan used on his way to the U.S. — to Dallas:

A random check of flights from Monrovia into Dallas-Fort Worth International indicate few would put passengers through added screening before they reach Texas. The travel broker site Skyscanner.com, for example, lists three itineraries for this Saturday, but none go to an airport with extra defenses. Wait a week until Oct. 18, and one does go via Atlanta, but the other two make their last connection in Europe before landing in Dallas.

Kayak.com brings similar results. None of the 10 itineraries available on those two Saturdays includes a screening stopover.

• From the Guinea capital of Conakry to Dallas:

Change the point of origin to the biggest airport among the three outbreak-stricken nations, and the picture doesn’t change much. Skyscanner and Kayak have 20 options to Dallas this Saturday that won’t go through one of the five beefed-up airports. However, eight flight plans will.

Substitute Houston for Dallas and mix up the dates, and the breakdown is similar in most situations. The numbers, however, are bigger.

• From Monrovia to Houston:

Skyscanner shows all five itineraries to Houston from Monrovia bypassing the extra screening, while Kayak shows eight doing the same thing on Oct. 16. Change the date to Oct. 24, and six of nine Skyscanner itineraries bypass the screening, while 12 of Kayak’s 18 flight plans avoid it as well.

• From Conakry to Houston:

A cursory glance at the Conakry-to-Houston flights for Oct. 11 shows passengers using 29 itineraries that avoid the screening, while 16 would pass through it, a cumulative tally from both flight brokers shows.

• From Monrovia to other U.S. destinations:

MarketWatch did a superficial check of flight plans just from Monrovia on random dates headed for various cities. More than half the flight plans for Philadelphia, Boston and Detroit didn’t route through the five screening airports. A handful of flights headed for Minneapolis-St. Paul, Charlotte, N.C., Los Angeles and Portland also would bypass the process.

Homeland Security officials were asked to provide methodology for determining how the 94% figure was reached but offered no response. Checking their math and thumbing through all possible international flights would prove too cumbersome, making it impossible to determine whether the figure is accurate.

The University of Texas’s McCormick says the point is moot, though, because the feds’ plan is fraught with potential problems.

Putting together an effective screening program that checks all passengers would be too “unwieldy”, he said. The five airports probably were selected as a pilot effort to see if more screening would be practical. But such a program could be fraught with difficulties, leading some passengers suffering from non-contagious malaria to be quarantined mistakenly.

“There are going to be plenty of false positives,” he said. “It’s going to focus on problems that probably don’t exist.”

If anyone showing obvious symptoms of Ebola tries to get on a plane in West Africa, it’s more likely they’ll be stopped there. If they aren’t showing symptoms and get on a plane, they’ll likely pass through screening here. He adds passengers like Duncan probably wouldn’t raise a red flag.

“I think it’s fraught with all sorts of issues that haven’t been thought out,” he said.