Senior citizens and frontline health workers may avail of second booster shots against coronavirus disease (COVID-19) ''effective immediately'', the Department of Health (DOH) said Wednesday.

"After careful study and consideration of the best available evidence, we shall now roll out effective immediately the second booster for our frontline health workers and senior citizens," said Health Undersecretary Myrna Cabotaje.

Approved as second booster shots are COVID-19 vaccines of Moderna and Pfizer.

In a statement, the Department of Health (DOH) said it released interim operational guidelines on giving the second COVID-19 vaccine booster doses to senior citizens and frontline healthcare workers.

"The second booster for our health workers and senior citizens will enhance protection given by the first booster and the primary series against all variants, including the recent Omicron subvariant BA.2.12.1," said Health Undersecretary Maria Rosario Vergeire.

Under the guidelines, the administration of the second booster doses for individuals 18 years old and above belonging to workers in essential health services, and all individuals 60 years old and above are eligible to get second booster shots.

The shots can be given at least four months after the administration of the first booster.

The second booster doses will be given to eligible individuals nationwide, but depending on the readiness of vaccination sites.

The DOH said 13, 674, 611 persons have received the first booster dose as of May 17 while 68, 769. 423 persons have gotten a complete dose. DMS