The Isle of Wight Council and the Island's NHS Trust are urging residents NOT to travel to the mainland for a coronavirus test.
The Isle of Wight Council says it is unacceptable that people struggling to book a test, either at the testing site at Newclose Cricket Ground or via post, are being offered alternative appointments that require them to travel to and from the mainland for a swab.
With people being offered slots at venues up to 75 miles away, the council has called on the government to adjust the national appointment system to take account of the Island's unique circumstances.
Meanwhile, a petition calling for the prevention of people crossing the Solent for a test has gathered more than 1,200 signatures. Huge concerns have been raised about people with symptoms - and even positive results - being forced to leave their vehicles and mix with others on the ferry.
Simon Bryant, the council's director of public health, said appointments for tests were made available on a daily basis - the evening before for the following morning and the morning before for later in the day.
He said:
"Therefore do not think that because there is no availability when you call or go online that means no availability at all for the foreseeable future. So please keep trying to get the test you need.
"Residents should not travel to mainland testing sites when symptomatic. There should be sufficient test availability for you to be tested here and if the system only offers a mainland testing site, please retry or request a home test.
"Of most importance is to only book a test if you have the symptoms of the coronavirus (high temperature, new, persistent cough and/or loss of taste and smell); this is when the current type of test is most effective.
"A test at any time will only be as good as the day it is taken and it is not a predictor of future wellbeing."