A periapical abscess is is a localised accumulation of pus around the end or the root of the tooth. The source of the infection is a necrotic (dead) pulp inside the tooth or a failing root canal treatment.
As opposed to an Acute Periapical Abscess which causes a lot of pain and swelling, a chronic abscess:
A chronic abscess will need treatment from a dentist after lockdown but as the symptoms are mild it should not cause an emergency during lockdown.
It is important to avoid it becoming an acute abscess so local measure to keep it clean should be taken:
If the abscess worsens and become acute see here for more details