The Public Health Agency (PHA) has urged anyone who is offered a smallpox vaccine to take it to protect themselves against monkeypox.
The PHA said the 27 cases in Northern Ireland were mainly seen in gay and bisexual men, but anyone could potentially catch the virus.
Some 1,120 vaccinations have been allocated to Northern Ireland and 2,500 people are currently eligible.
The virus is not new but only arrived in Northern Ireland in May 2022.
Vaccination against smallpox has been proven to be 85% effective in preventing monkeypox.
The PHA said that an individual's eligibility for vaccination depends on a number of factors, similar to the criteria used to assess those eligible for HIV pre-exposure prophylaxis (PrEP), even if they are already living with HIV.
Dr David Cromie of the PHA said: "Some eligible people will be asked to wait while stocks of vaccine are manufactured and distributed.
"Until the delivery of further doses in September, GUM clinics will continue to vaccinate in line with any residual supplies, and work to ensure that those who are not already in touch with services know where and how to access vaccination".
He said there was no need to phone for an appointment as GUM clinics keep a record of those eligible so that they can be invited forward for vaccination.
Although cases remain steady Dr Cromie urged "ongoing vigilance" he said it was too soon to determine if the low levels will be sustained.
It can take up to three weeks for symptoms to appear after being in contact with someone with monkeypox.
"We are continuing to work with partners to ensure people in the gay and bisexual men who have sex with men (gbMSM) community know the signs and symptoms of monkeypox and how to seek help if they have concerns," he said.
"Before attending any group events including bars, clubs and outside events, check yourself for monkeypox symptoms, including rashes and blisters," he added.
He said anyone who had symptoms should not attend events or engage in any physical contact until they have called a GUM clinic and been seen by a healthcare worker.
Monkeypox is caused by the monkeypox virus, a member of the same family of viruses as smallpox, although it is much less severe and experts say chances of infection are low.
It occurs mostly in remote parts of central and west African countries, near tropical rainforests. In those regions, there have been more than 1,200 cases of monkeypox since the start of the year.
Two main strains of the virus – west African and central African – are known to exist, and it is the milder one from west Africa which is now circulating in other regions of the world.
Meanwhile, the Department of Health in the Republic of Ireland has confirmed the establishment of a strategic advisory group on monkeypox.
It said the group will advise the minister and the Irish government on how best to respond to the outbreak.
The Interim Chief Medical Officer has said that she expects Ireland to receive additional monkeypox vaccines by December.
Speaking on RTÉ's News At One, Professor Breda Smyth said she cannot yet put a specific figure on that allocation.
There are 113 cases of monkeypox in the Republic of Ireland at present, which have been diagnosed over an 11-week period.
Four people have been admitted to hospital with the virus.
Prof Fiona Lyons is a consultant in genitourinary and HIV medicine at St James's Hospital, Dublin.
She told RTÉ's Morning Ireland that the Health Service Executive estimates that up to 6,500 people are at heightened risk and would "benefit" from a vaccine, but current supplies will only allow vaccination for around 10% of them.
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