May 21 (Reuters) - Moderna said on Wednesday it has withdrawn an application seeking approval for its flu and COVID combination vaccine candidate to wait for efficacy data from a late-stage trial of its influenza shot, which is due later this year.

The delay was largely expected after Moderna said earlier this month that it does not anticipate approval of the shot until 2026 due to the need for more data on the flu vaccine.

Moderna shares dropped 4.4% in morning trading. The shares have fallen over 35% this year.

However, the application withdrawal is the latest sign of increased regulatory scrutiny of the vaccine approval process since Robert F. Kennedy Jr. took the top U.S. health job earlier this year.

Moderna's decision comes a day after the U.S. Food and Drug Administration said it would require new clinical trials for approval of annual COVID-19 boosters for healthy people under 65.

The combination shot comprises a new COVID vaccine and an influenza vaccine, both under development by Moderna.

The company has previously said it does not expect a delay in the FDA's decision for the next-generation COVID vaccine, which is due by the end of the month.

Shares of the company have been battered by declining COVID revenue as well as investor concerns spurred by the appointment of Kennedy, who is a vaccine skeptic, as secretary of the U.S. Department of Health and Human Services.

Moderna has been banking on revenue from newer mRNA shots to make up for falling sales of its COVID vaccine and less-than-expected uptake of its respiratory syncytial virus vaccine.

The FDA last week approved rival Novavax's COVID-19 vaccine more than a month after missing the deadline for the shot's approval, and limited its use to people with conditions that put them at risk due to the illness.