This paper diagnoses the reading skills at the onset of second grade after one (final) trimester of first grade, with online schooling as a result of COVID-19. It also describes and assesses the impact of a Reading Skills Consolidating Program conducted with second graders during the first weeks of the school year. This intervention program focuses on the promotion of letter-sound, phonemic awareness, decoding and spelling. The intervention was implemented with 446-second graders (224 boys and 208 girls), preceded and followed by a reading assessment. Results were analyzed with an intra (pre- and post-test) group design. A paired sample t-test indicated the presence of statistically significant differences between the two assessment moments, with higher values at the post-test. At the pre-test, there was a significantly higher than the normally expected percentage of students with a reading level on or below the 10th percentile along with a significantly worse performance among low Socioeconomic Status (SES) students. The post-test revealed a positive impact of the training program, as indicated by (i) a decrease to about half of the number of students at or below the 10th percentile, (ii) an increase of 20% of students with reading skills at or above the 30th percentile and (iii) the difference decrease in reading skills in a result of SES.