If a Catholic can attend Mass, they must do so, in person. The rule for in-person attendance applies to healthy people capable of getting there. Generally, if you are not sick, or have a major health concern, you should attend Mass in person. A suggested rule: if a person can go to work or engage in social activities, they are likely able to attend Mass. For those who cannot attend Mass because of health or duty, the best they may be able to do is attend online. By duty, we refer to persons such as first responders who may work 24 hour shifts. For those with sincere intentions unable to attend Mass, livestreaming provides a lifeline. For the rest of us, we must attend every Sunday and Holy Day of Obligation.