DUBLIN—Ireland will no longer require vaccinated arriving travelers to present a negative COVID-19 test, Prime Minister Micheál Martin said on Wednesday. A government spokesman said the change will take effect on Thursday. Unvaccinated travelers will still be required to show a negative PCR test taken no more than 72 hours before arrival. Ireland introduced the testing measure a month ago to slow the spread of the new Omicron coronavirus variant. Omicron now accounts for almost all Irish infections, which have rocketed to record levels in the last two weeks. Martin also said he believed Ireland’s current restrictions to slow the spread of infection are effective and that it remained to be seen whether health chiefs will suggest any changes later this week. The government tightened COVID-19 restrictions last month, shutting nightclubs and ordering pubs and restaurants to close at 8 p.m. “There will be a challenging number of weeks in …