The Travel Corporation's Trafalgar, Costsaver, Brendan Vacations and Contiki tour companies have instituted a Covid vaccination requirement for all adult guests, effective Sept. 1.

Under the new policy, adult travelers on trips departing Sept. 1 or later will need to show documented proof of having received an approved Covid-19 vaccine from either Pfizer, Moderna, Astra Zeneca or Johnson & Johnson, with the final dose of the vaccine administered at least 14 days prior to the start of their trip.

According to Melissa da Silva, U.S. president of Trafalgar, Contiki, Brendan Vacations and Costsaver, the requirement is intended to "ensure that our guests are not only protected, but also enjoy their vacation as seamlessly as possible."

The policy is expected to remain in effect at least until Dec. 31.

Insight Vacations and Luxury Gold, which are also part of The Travel Corporation brand portfolio, have announced similar Covid vaccination requirements.

Both upscale tour operators will mandate that travelers be fully vaccinated for all trips -- excluding itineraries in Australia and New Zealand -- between Sept. 1 to the end of 2021.

Proof of vaccination will need to be provided before joining an Insight Vacations or Luxury Gold tour, as well as upon arrival to the destination. Guests can provide either an electronic or paper Covid vaccination certificate showing the date and time of their vaccinations, with the final dose required to have been received at least 15 days before the start of the tour.

Approved Covid vaccines include those from Pfizer, Moderna, Astra Zeneca Vaxzevria or Johnson & Johnson.

In a statement, Insight Vacations and Luxury Gold emphasized that all guests will still need to comply with any testing requirements imposed by airlines and/or local governments.

This report was updated on Aug. 13 to add information on Insight Vacations and Luxury Gold.