MS Ireland has said its fundraising is down by around 33% from the previous year because of the pandemic.
There are 9,000 people in Ireland living with multiple sclerosis, for which there is no known cause or cure.
It is the most commonly diagnosed neurological condition in young people in Ireland and three out of every four diagnoses are female.
A condition of the brain and spinal cord, some of the symptoms of MS include reduced mobility, fatigue, and changes in sensation, memory and concentration.
A virtual balloon race is to take place to mark World MS Day, with a balloon flying for each person who has the condition.
Cork woman Clare Kelliher, who is 33, was diagnosed with MS six years ago.
The mother of a one-year-old boy, named Sam, said sometimes living with her symptoms can be difficult but with the support of her family, friends and MS Ireland helps her through.
She urged people to be kind to each other.
She said: "My life with MS will never be normal but it is a great life and I wouldn't change a thing about it.
"We all have invisible challenges in our lives so it is important to be kind to others as you never know what's going on.
"It is also important to be kind and forgiving to yourself. When I fall in public, I no longer get embarrassed, I just laugh it off and walk slower until the next time."