State health officials have said that Oregon's vaccine-exemption rate has shown a fall. On Friday, the Oregon Health Authority said more than 600 fewer kindergarten students have filed for nonmedical exemptions for this school year.

Officials said that the drop may have a link to a new law, requiring parents seeking an exemption to talk to a doctor or watch an online video regarding the benefits of vaccines. The law went into effect previous March.

As per the data, 5.8% of all kindergarteners that is 2,693 students have claimed religious, philosophical or other nonmedical exemption to one or more required vaccines in March 2015. It has fallen as compared to 7%, or 3,331 students, who opted out in March 2014.

Last year, Oregon had the nation's highest exemption rate. At present it is unclear that whether the state still has the highest rate or not, as the updated national data have not been released yet. The US Centers for Disease Control and Prevention will release that ranking at the end of this summer.

Oregon wants all children in public and private schools, preschools, Head Start and certified child-care facilities to have updated immunizations, or have an exemption.

State health officials said that they are worried that some schools won't be able to achieve 'herd immunity', which means that their enough children will not be vaccinated to prevent a disease from spreading.

Stacy de Assis Matthews of the Oregon Immunization Program said that both California and Washington, which instituted vaccine-education laws in recent years, have also seen fall in their exemption rates.

The issue of exemptions took the flame earlier this year, after a measles outbreak that began at Disneyland in California and spread to other states.

But legislation in Oregon which has been aiming to eliminate personal, religious and philosophical exemptions was abandoned due to formidable opposition from parents. They argued that it took away their medical freedom and right to informed consent.