BERLIN, Dec 21 (Reuters) - Germany"s STIKO vaccine authority on Tuesday shortened the recommended period between a second coronavirus shot and a booster to three months from six, reflecting the increasing presence of the highly infectious Omicron variant. The authority said anyone over age 18 should have a booster using an mRNA vaccine three months after completing a two-shot course of COVID-19 vaccines. STIKO previously recommended anyone fully vaccinated with an mRNA vaccine should wait six months after their last shot. For the one-shot Johnson & Johnson vaccine, that period remains four weeks. STIKO also recommended that anyone over age 12 who was infected with the coronavirus should receive a shot at least three months after they recovered. Previously the recommendation was six months. The elderly or people with pre-existing conditions should be prioritised for booster shots, the committee added. Some 70.4% of the population has had two vaccinations and 32.6% have received a booster. While data remains limited, half a dozen laboratory studies have shown that an initial course of COVID-19 vaccines is not enough to halt infection from Omicron, but a booster may help. read more