The numbers of most sexually transmitted infections (STIs) have fallen dramatically since the Covid-19 lockdown began.
However, it is unclear if the reason is a decrease in sexual activity because of lockdown, or a change in the testing regime because of the coronavirus.
Figures released by the Health Protection Surveillance Centre show trichomoniasis numbers down 35pc when compared to the same period in 2019, syphilis numbers down more than 20pc, genital herpes down almost 20pc, chlamydia down nearly 7pc, and gonorrhoea down more than 2pc.
However, there has also been a large increase of more than 36pc in HIV infections.
Health experts say it is too early to tell if the downward trend in STIs is directly associated with a drop in sexual encounters since society was put on lockdown.
"The reasons for decline in notification of most of the STIs other than HIV may be multi-factorial," said a Department of Health spokesperson.
The decline could be attributed to fewer sexual encounters due to lockdown, but also due to a decreased attendance at STI clinics and GPs for diagnosis and treatment of acute infections, they said.
"There could also be delays in notification on CIDR (Computerised Infectious Disease Reporting) due to staff being allocated to Covid-19 activities," they added.
"It is most likely a combination of these factors, but we can't say for sure at this stage."
In explaining the rise in reported HIV cases, the spokesperson said it was a continuing trend since 2015 and the number of cases reported in the first 16 weeks of this year exceeded the same period in 2019 by 53 cases.
"As numbers notified can fluctuate from month to month it is important to monitor the trend over time," they said.
"Unlike many of the other STIs, HIV diagnosis is often made upon screening when attending an STI clinic, and may reflect an old rather than acute infection."
Stephen O'Hare of HIV Ireland, a group that advocates for people living with the virus, says the drop in numbers for most infections is likely down to a drop in testing or test sample analysis due to resources being shifted toward Covid-19.
He fears there is potential for a large spike in figures when testing resumes.
"If people are not being tested, for whatever reason, then we could have a lag in information, and when we get to the end of the summer we could see a spike in STIs," he said.
"If people aren't being tested, they may not know they have an infection, so they don't access treatment, and potentially spread the infection, which could lead to a spike in figures.
"There is a cohort of people who get tested regularly, especially those with multiple sexual partners. Pre-Covid there was already enough pressure on the system, but now we are definitely not meeting demand for testing."
HIV Ireland works with St James's Hospital in its own testing system, but it says that a move to Covid-19 testing in the hospital has meant HIV Ireland cannot carry out testing at the moment.
"We are fully supportive of the HSE efforts to control Covid-19," said Mr O'Hare.
He said a possible reason for the spike in detected HIV cases could be because in November last year free access to a drug called Prep was introduced.
Applicants had to undergo a test for HIV before accessing it, and this may have found some undetected HIV cases.
"The increase in testing may be the reason there was an increase in numbers," he said.
In the first 16 weeks of this year the age group presenting with most STIs was in the 20-24 bracket with 1,329, followed by the 25-29 bracket with 902, and the 30-34 bracket with 646.
Chlamydia was the most prevalent STI reported in the first 16 weeks of this year, with 2,506 cases, followed by gonorrhoea with 878 cases, genital herpes at 416, and HIV at 198.